ESlint JSdoc (#2148)

* Install eslint-plugin-jsdoc

* Initial rules setup

* Update lists

* Use @returns rather than @return

* Remove error throwing code which is never executed

* Fix issues relating to @throws

* General error fixes

* Update Display type documentation

* Various doc fixes

* Fix invalid tuple syntax

* Doc updates

* Remove unused

* Doc updates

* Enable jsdoc/require-returns

* Update rules

* Update remaining rules

30 files changed, 384 insertions, 244 deletions

diff --git a/ext/js/app/frontend.js b/ext/js/app/frontend.js
index 634408d9..f3b925c3 100644
--- a/ext/js/app/frontend.js
+++ b/ext/js/app/frontend.js
@@ -27,7 +27,7 @@
 class Frontend {
     /**
      * Creates a new instance.
-     * @param {object} details
+     * @param {object} details Details about how to set up the instance.
      * @param {string} details.pageType The type of page, one of 'web', 'popup', or 'search'.
      * @param {PopupFactory} details.popupFactory A PopupFactory instance to use for generating popups.
      * @param {number} details.depth The nesting depth value of the popup.
diff --git a/ext/js/app/popup-factory.js b/ext/js/app/popup-factory.js
index bef687ff..112fa963 100644
--- a/ext/js/app/popup-factory.js
+++ b/ext/js/app/popup-factory.js
@@ -63,7 +63,7 @@ class PopupFactory {
 
     /**
      * Gets or creates a popup based on a set of parameters
-     * @param {object} details
+     * @param {object} details Details about how to acquire the popup.
      * @param {?number} [details.frameId] The ID of the frame that should host the popup.
      * @param {?string} [details.id] A specific ID used to find an existing popup, or to assign to the new popup.
      * @param {?string} [details.parentPopupId] The ID of the parent popup.
diff --git a/ext/js/app/popup-proxy.js b/ext/js/app/popup-proxy.js
index 2bf81d0a..77d87520 100644
--- a/ext/js/app/popup-proxy.js
+++ b/ext/js/app/popup-proxy.js
@@ -22,7 +22,7 @@
 class PopupProxy extends EventDispatcher {
     /**
      * Creates a new instance.
-     * @param {object} details
+     * @param {object} details Details about how to set up the instance.
      * @param {string} details.id The ID of the popup.
      * @param {number} details.depth The depth of the popup.
      * @param {number} details.frameId The ID of the host frame.
@@ -66,10 +66,10 @@ class PopupProxy extends EventDispatcher {
 
     /**
      * Attempts to set the parent popup.
-     * @param {Popup} value
-     * @throws Throws an error, since this class doesn't support a direct parent.
+     * @param {Popup} _value The parent to assign.
+     * @throws {Error} Throws an error, since this class doesn't support a direct parent.
      */
-    set parent(value) {
+    set parent(_value) {
         throw new Error('Not supported on PopupProxy');
     }
 
@@ -84,10 +84,10 @@ class PopupProxy extends EventDispatcher {
 
     /**
      * Attempts to set the child popup.
-     * @param {Popup} value
-     * @throws Throws an error, since this class doesn't support children.
+     * @param {Popup} _child The child to assign.
+     * @throws {Error} Throws an error, since this class doesn't support children.
      */
-    set child(value) {
+    set child(_child) {
         throw new Error('Not supported on PopupProxy');
     }
 
@@ -233,7 +233,6 @@ class PopupProxy extends EventDispatcher {
 
     /**
      * Returns whether or not the popup is currently visible, synchronously.
-     * @returns {boolean} `true` if the popup is visible, `false` otherwise.
      * @throws An exception is thrown for `PopupProxy` since it cannot synchronously detect visibility.
      */
     isVisibleSync() {
diff --git a/ext/js/app/popup-window.js b/ext/js/app/popup-window.js
index 6a63a9cb..19753906 100644
--- a/ext/js/app/popup-window.js
+++ b/ext/js/app/popup-window.js
@@ -21,7 +21,7 @@
 class PopupWindow extends EventDispatcher {
     /**
      * Creates a new instance.
-     * @param {object} details
+     * @param {object} details Details about how to set up the instance.
      * @param {string} details.id The ID of the popup.
      * @param {number} details.depth The depth of the popup.
      * @param {number} details.frameId The ID of the host frame.
@@ -53,10 +53,10 @@ class PopupWindow extends EventDispatcher {
     /**
      * The parent of the popup, which is always `null` for `PopupWindow` instances,
      * since any potential parent popups are in a different frame.
-     * @param {Popup} value
-     * @type {Popup}
+     * @param {Popup} _value The parent to assign.
+     * @throws {Error} Throws an error, since this class doesn't support children.
      */
-    set parent(value) {
+    set parent(_value) {
         throw new Error('Not supported on PopupWindow');
     }
 
@@ -71,10 +71,10 @@ class PopupWindow extends EventDispatcher {
 
     /**
      * Attempts to set the child popup.
-     * @param {Popup} value
+     * @param {Popup} _value The child to assign.
      * @throws Throws an error, since this class doesn't support children.
      */
-    set child(value) {
+    set child(_value) {
         throw new Error('Not supported on PopupWindow');
     }
 
@@ -168,7 +168,7 @@ class PopupWindow extends EventDispatcher {
 
     /**
      * Shows and updates the positioning and content of the popup.
-     * @param {Popup.ContentDetails} details Settings for the outer popup.
+     * @param {Popup.ContentDetails} _details Settings for the outer popup.
      * @param {Display.ContentDetails} displayDetails The details parameter passed to `Display.setContent`.
      * @returns {Promise<void>}
      */
@@ -180,6 +180,7 @@ class PopupWindow extends EventDispatcher {
     /**
      * Sets the custom styles for the popup content.
      * @param {string} css The CSS rules.
+     * @returns {Promise<void>}
      */
     setCustomCss(css) {
         return this._invoke(false, 'Display.setCustomCss', {id: this._id, css});
@@ -187,6 +188,7 @@ class PopupWindow extends EventDispatcher {
 
     /**
      * Stops the audio auto-play timer, if one has started.
+     * @returns {Promise<void>}
      */
     clearAutoPlayTimer() {
         return this._invoke(false, 'Display.clearAutoPlayTimer', {id: this._id});
@@ -194,7 +196,7 @@ class PopupWindow extends EventDispatcher {
 
     /**
      * Sets the scaling factor of the popup content.
-     * @param {number} scale The scaling factor.
+     * @param {number} _scale The scaling factor.
      */
     setContentScale(_scale) {
         // NOP
@@ -202,7 +204,6 @@ class PopupWindow extends EventDispatcher {
 
     /**
      * Returns whether or not the popup is currently visible, synchronously.
-     * @returns {boolean} `true` if the popup is visible, `false` otherwise.
      * @throws An exception is thrown for `PopupWindow` since it cannot synchronously detect visibility.
      */
     isVisibleSync() {
diff --git a/ext/js/app/popup.js b/ext/js/app/popup.js
index e3ac4dc3..9ca2165d 100644
--- a/ext/js/app/popup.js
+++ b/ext/js/app/popup.js
@@ -66,7 +66,7 @@ class Popup extends EventDispatcher {
 
     /**
      * Creates a new instance.
-     * @param {object} details
+     * @param {object} details The details used to construct the new instance.
      * @param {string} details.id The ID of the popup.
      * @param {number} details.depth The depth of the popup.
      * @param {number} details.frameId The ID of the host frame.
@@ -673,9 +673,11 @@ class Popup extends EventDispatcher {
     }
 
     /**
-     * @param {Rect[]} sourceRects
-     * @param {string} writingMode
-     * @returns {SizeRect}
+     * Computes the position where the popup should be placed relative to the source content.
+     * @param {Rect[]} sourceRects The rectangles of the source content.
+     * @param {string} writingMode The CSS writing mode of the source text.
+     * @param {Rect} viewport The viewport that the popup can be placed within.
+     * @returns {SizeRect} The calculated rectangle for where to position the popup.
      */
     _getPosition(sourceRects, writingMode, viewport) {
         const scale = this._contentScale;
@@ -720,7 +722,15 @@ class Popup extends EventDispatcher {
     }
 
     /**
-     * @returns {SizeRect}
+     * Computes the position where the popup should be placed for horizontal text.
+     * @param {Rect} sourceRect The rectangle of the source content.
+     * @param {number} frameWidth The preferred width of the frame.
+     * @param {number} frameHeight The preferred height of the frame.
+     * @param {Rect} viewport The viewport that the frame can be placed within.
+     * @param {number} horizontalOffset The horizontal offset from the source rect that the popup will be placed.
+     * @param {number} verticalOffset The vertical offset from the source rect that the popup will be placed.
+     * @param {boolean} preferBelow Whether or not the popup is preferred to be placed below the source content.
+     * @returns {SizeRect} The calculated rectangle for where to position the popup.
      */
     _getPositionForHorizontalText(sourceRect, frameWidth, frameHeight, viewport, horizontalOffset, verticalOffset, preferBelow) {
         const [left, width, after] = this._getConstrainedPosition(
@@ -743,7 +753,15 @@ class Popup extends EventDispatcher {
     }
 
     /**
-     * @returns {SizeRect}
+     * Computes the position where the popup should be placed for vertical text.
+     * @param {Rect} sourceRect The rectangle of the source content.
+     * @param {number} frameWidth The preferred width of the frame.
+     * @param {number} frameHeight The preferred height of the frame.
+     * @param {Rect} viewport The viewport that the frame can be placed within.
+     * @param {number} horizontalOffset The horizontal offset from the source rect that the popup will be placed.
+     * @param {number} verticalOffset The vertical offset from the source rect that the popup will be placed.
+     * @param {boolean} preferRight Whether or not the popup is preferred to be placed to the right of the source content.
+     * @returns {SizeRect} The calculated rectangle for where to position the popup.
      */
     _getPositionForVerticalText(sourceRect, frameWidth, frameHeight, viewport, horizontalOffset, verticalOffset, preferRight) {
         const [left, width, after] = this._getConstrainedPositionBinary(
@@ -824,6 +842,11 @@ class Popup extends EventDispatcher {
         return [position, size, after];
     }
 
+    /**
+     * Gets the visual viewport.
+     * @param {boolean} useVisualViewport Whether or not the `window.visualViewport` should be used.
+     * @returns {Rect} The rectangle of the visual viewport.
+     */
     _getViewport(useVisualViewport) {
         const visualViewport = window.visualViewport;
         if (visualViewport !== null && typeof visualViewport === 'object') {
@@ -887,8 +910,9 @@ class Popup extends EventDispatcher {
     }
 
     /**
-     * @param {Rect[]} sourceRects
-     * @returns {Rect}
+     * Computes the bounding rectangle for a set of rectangles.
+     * @param {Rect[]} sourceRects An array of rectangles.
+     * @returns {Rect} The bounding rectangle for all of the source rectangles.
      */
     _getBoundingSourceRect(sourceRects) {
         switch (sourceRects.length) {
@@ -907,10 +931,11 @@ class Popup extends EventDispatcher {
     }
 
     /**
-     * @param {SizeRect} sizeRect
-     * @param {Rect[]} sourceRects
-     * @param {number} ignoreIndex
-     * @returns {boolean}
+     * Checks whether or not a rectangle is overlapping any other rectangles.
+     * @param {SizeRect} sizeRect The rectangles to check for overlaps.
+     * @param {Rect[]} sourceRects The list of rectangles to compare against.
+     * @param {number} ignoreIndex The index of an item in `sourceRects` to ignore.
+     * @returns {boolean} `true` if `sizeRect` overlaps any one of `sourceRects`, excluding `sourceRects[ignoreIndex]`; `false` otherwise.
      */
     _isOverlapping(sizeRect, sourceRects, ignoreIndex) {
         const {left, top} = sizeRect;
diff --git a/ext/js/app/theme-controller.js b/ext/js/app/theme-controller.js
index 4ee82c52..6a95e2d7 100644
--- a/ext/js/app/theme-controller.js
+++ b/ext/js/app/theme-controller.js
@@ -174,7 +174,7 @@ class ThemeController {
 
     /**
      * Adds the value of a CSS color to an accumulation target.
-     * @param {[number, number, number]} target The target color buffer to accumulate into.
+     * @param {number[]} target The target color buffer to accumulate into, as an array of [r, g, b].
      * @param {string|*} cssColor The CSS color value to add to the target. If this value is not a string,
      *   the target will not be modified.
      */
@@ -196,7 +196,7 @@ class ThemeController {
     /**
      * Decomposes a CSS color string into its RGBA values.
      * @param {string} cssColor The color value to decompose. This value is expected to be in the form RGB(r, g, b) or RGBA(r, g, b, a).
-     * @returns {?[number, number, number, number]} The color and alpha values. The color component values range from [0, 255], and the alpha ranges from [0, 1].
+     * @returns {?number[]} The color and alpha values as [r, g, b, a]. The color component values range from [0, 255], and the alpha ranges from [0, 1].
      */
     _getColorInfo(cssColor) {
         const m = /^\s*rgba?\s*\(\s*(\d+)\s*,\s*(\d+)\s*,\s*(\d+)\s*(?:,\s*([\d.]+)\s*)?\)\s*$/.exec(cssColor);
diff --git a/ext/js/background/profile-conditions-util.js b/ext/js/background/profile-conditions-util.js
index fd2991f8..e9bd7a19 100644
--- a/ext/js/background/profile-conditions-util.js
+++ b/ext/js/background/profile-conditions-util.js
@@ -24,6 +24,20 @@
  */
 class ProfileConditionsUtil {
     /**
+     * A group of conditions.
+     * @typedef {object} ProfileConditionGroup
+     * @property {ProfileCondition[]} conditions The list of conditions for this group.
+     */
+
+    /**
+     * A single condition.
+     * @typedef {object} ProfileCondition
+     * @property {string} type The type of the condition.
+     * @property {string} operator The condition operator.
+     * @property {string} value The value to compare against.
+     */
+
+    /**
      * Creates a new instance.
      */
     constructor() {
@@ -78,20 +92,9 @@ class ProfileConditionsUtil {
 
     /**
      * Creates a new JSON schema descriptor for the given set of condition groups.
-     * @param conditionGroups An array of condition groups in the following format:
-     *  conditionGroups = [
-     *      {
-     *          conditions: [
-     *              {
-     *                  type: (condition type: string),
-     *                  operator: (condition sub-type: string),
-     *                  value: (value to compare against: string)
-     *              },
-     *              ...
-     *          ]
-     *      },
-     *      ...
-     *  ]
+     * @param {ProfileConditionGroup[]} conditionGroups An array of condition groups.
+     *   For a profile match, all of the items must return successfully in at least one of the groups.
+     * @returns {JsonSchema} A new `JsonSchema` object.
      */
     createSchema(conditionGroups) {
         const anyOf = [];
@@ -125,8 +128,8 @@ class ProfileConditionsUtil {
     /**
      * Creates a normalized version of the context object to test,
      * assigning dependent fields as needed.
-     * @param context A context object which is used during schema validation.
-     * @returns A normalized context object.
+     * @param {object} context A context object which is used during schema validation.
+     * @returns {object} A normalized context object.
      */
     normalizeContext(context) {
         const normalizedContext = Object.assign({}, context);
diff --git a/ext/js/comm/clipboard-reader.js b/ext/js/comm/clipboard-reader.js
index 7a4744ca..aaf4dcd8 100644
--- a/ext/js/comm/clipboard-reader.js
+++ b/ext/js/comm/clipboard-reader.js
@@ -25,9 +25,10 @@
 class ClipboardReader {
     /**
      * Creates a new instances of a clipboard reader.
-     * @param document The Document object to be used, or null for no support.
-     * @param pasteTargetSelector The selector for the paste target element.
-     * @param imagePasteTargetSelector The selector for the image paste target element.
+     * @param {object} details Details about how to set up the instance.
+     * @param {?Document} details.document The Document object to be used, or null for no support.
+     * @param {?string} details.pasteTargetSelector The selector for the paste target element.
+     * @param {?string} details.imagePasteTargetSelector The selector for the image paste target element.
      */
     constructor({document=null, pasteTargetSelector=null, imagePasteTargetSelector=null}) {
         this._document = document;
@@ -40,6 +41,7 @@ class ClipboardReader {
 
     /**
      * Gets the browser being used.
+     * @type {?string}
      */
     get browser() {
         return this._browser;
@@ -54,8 +56,8 @@ class ClipboardReader {
 
     /**
      * Gets the text in the clipboard.
-     * @returns A string containing the clipboard text.
-     * @throws Error if not supported.
+     * @returns {string} A string containing the clipboard text.
+     * @throws {Error} Error if not supported.
      */
     async getText() {
         /*
@@ -103,8 +105,8 @@ class ClipboardReader {
 
     /**
      * Gets the first image in the clipboard.
-     * @returns A string containing a data URL of the image file, or null if no image was found.
-     * @throws Error if not supported.
+     * @returns {string} A string containing a data URL of the image file, or null if no image was found.
+     * @throws {Error} Error if not supported.
      */
     async getImage() {
         // See browser-specific notes in getText
diff --git a/ext/js/comm/frame-ancestry-handler.js b/ext/js/comm/frame-ancestry-handler.js
index cff31ce0..56daafe9 100644
--- a/ext/js/comm/frame-ancestry-handler.js
+++ b/ext/js/comm/frame-ancestry-handler.js
@@ -24,7 +24,7 @@
 class FrameAncestryHandler {
     /**
      * Creates a new instance.
-     * @param frameId The frame ID of the current frame the instance is instantiated in.
+     * @param {number} frameId The frame ID of the current frame the instance is instantiated in.
      */
     constructor(frameId) {
         this._frameId = frameId;
@@ -37,6 +37,7 @@ class FrameAncestryHandler {
 
     /**
      * Gets the frame ID that the instance is instantiated in.
+     * @type {number}
      */
     get frameId() {
         return this._frameId;
@@ -53,7 +54,7 @@ class FrameAncestryHandler {
 
     /**
      * Returns whether or not this frame is the root frame in the tab.
-     * @returns `true` if it is the root, otherwise `false`.
+     * @returns {boolean} `true` if it is the root, otherwise `false`.
      */
     isRootFrame() {
         return (window === window.parent);
@@ -63,8 +64,7 @@ class FrameAncestryHandler {
      * Gets the frame ancestry information for the current frame. If the frame is the
      * root frame, an empty array is returned. Otherwise, an array of frame IDs is returned,
      * starting from the nearest ancestor.
-     * @param timeout The maximum time to wait to receive a response to frame information requests.
-     * @returns An array of frame IDs corresponding to the ancestors of the current frame.
+     * @returns {number[]} An array of frame IDs corresponding to the ancestors of the current frame.
      */
     async getFrameAncestryInfo() {
         if (this._getFrameAncestryInfoPromise === null) {
@@ -77,8 +77,8 @@ class FrameAncestryHandler {
      * Gets the frame element of a child frame given a frame ID.
      * For this function to work, the `getFrameAncestryInfo` function needs to have
      * been invoked previously.
-     * @param frameId The frame ID of the child frame to get.
-     * @returns The element corresponding to the frame with ID `frameId`, otherwise `null`.
+     * @param {number} frameId The frame ID of the child frame to get.
+     * @returns {HTMLElement} The element corresponding to the frame with ID `frameId`, otherwise `null`.
      */
     getChildFrameElement(frameId) {
         const frameInfo = this._childFrameMap.get(frameId);
diff --git a/ext/js/comm/mecab.js b/ext/js/comm/mecab.js
index 9be8b75f..24364588 100644
--- a/ext/js/comm/mecab.js
+++ b/ext/js/comm/mecab.js
@@ -21,6 +21,21 @@
  */
 class Mecab {
     /**
+     * The resulting data from an invocation of `parseText`.
+     * @typedef {object} ParseResult
+     * @property {string} name The dictionary name for the parsed result.
+     * @property {ParseTerm[]} lines The resulting parsed terms.
+     */
+
+    /**
+     * A fragment of the parsed text.
+     * @typedef {object} ParseFragment
+     * @property {string} term The term.
+     * @property {string} reading The reading of the term.
+     * @property {string} source The source text.
+     */
+
+    /**
      * Creates a new instance of the class.
      */
     constructor() {
@@ -37,6 +52,7 @@ class Mecab {
 
     /**
      * Returns whether or not the component is enabled.
+     * @returns {boolean} Whether or not the object is enabled.
      */
     isEnabled() {
         return this._enabled;
@@ -44,7 +60,7 @@ class Mecab {
 
     /**
      * Changes whether or not the component connection is enabled.
-     * @param enabled A boolean indicating whether or not the component should be enabled.
+     * @param {boolean} enabled A boolean indicating whether or not the component should be enabled.
      */
     setEnabled(enabled) {
         this._enabled = !!enabled;
@@ -64,7 +80,7 @@ class Mecab {
 
     /**
      * Returns whether or not the connection to the native application is active.
-     * @returns `true` if the connection is active, `false` otherwise.
+     * @returns {boolean} `true` if the connection is active, `false` otherwise.
      */
     isConnected() {
         return (this._port !== null);
@@ -72,7 +88,7 @@ class Mecab {
 
     /**
      * Returns whether or not any invocation is currently active.
-     * @returns `true` if an invocation is active, `false` otherwise.
+     * @returns {boolean} `true` if an invocation is active, `false` otherwise.
      */
     isActive() {
         return (this._invocations.size > 0);
@@ -80,7 +96,7 @@ class Mecab {
 
     /**
      * Gets the local API version being used.
-     * @returns An integer representing the API version that Yomichan uses.
+     * @returns {number} An integer representing the API version that Yomichan uses.
      */
     getLocalVersion() {
         return this._version;
@@ -88,7 +104,7 @@ class Mecab {
 
     /**
      * Gets the version of the MeCab component.
-     * @returns The version of the MeCab component, or `null` if the component was not found.
+     * @returns {?number} The version of the MeCab component, or `null` if the component was not found.
      */
     async getVersion() {
         try {
@@ -115,8 +131,8 @@ class Mecab {
      *     ...
      * ]
      * ```
-     * @param text The string to parse.
-     * @returns A collection of parsing results of the text.
+     * @param {string} text The string to parse.
+     * @returns {ParseResult[]} A collection of parsing results of the text.
      */
     async parseText(text) {
         await this._setupPort();
diff --git a/ext/js/core.js b/ext/js/core.js
index 517642a2..9b5734f2 100644
--- a/ext/js/core.js
+++ b/ext/js/core.js
@@ -250,7 +250,7 @@ function generateId(length) {
 
 /**
  * Creates an unresolved promise that can be resolved later, outside the promise's executor function.
- * @returns {{promise: Promise, resolve: function, reject: function}} An object `{promise, resolve, reject}`, containing the promise and the resolve/reject functions.
+ * @returns {{promise: Promise, resolve: Function, reject: Function}} An object `{promise, resolve, reject}`, containing the promise and the resolve/reject functions.
  */
 function deferPromise() {
     let resolve;
@@ -349,15 +349,15 @@ function promiseAnimationFrame(timeout=null) {
 /**
  * Invokes a standard message handler. This function is used to react and respond
  * to communication messages within the extension.
- * @param {object} details
- * @param {function} details.handler A handler function which is passed `params` and `...extraArgs` as arguments.
+ * @param {object} details Details about how to handle messages.
+ * @param {Function} details.handler A handler function which is passed `params` and `...extraArgs` as arguments.
  * @param {boolean|string} details.async Whether or not the handler is async or not. Values include `false`, `true`, or `'dynamic'`.
  *   When the value is `'dynamic'`, the handler should return an object of the format `{async: boolean, result: any}`.
  * @param {object} params Information which was passed with the original message.
- * @param {function} callback A callback function which is invoked after the handler has completed. The value passed
+ * @param {Function} callback A callback function which is invoked after the handler has completed. The value passed
  *   to the function is in the format:
- *   * `{result: any}` if the handler invoked successfully.
- *   * `{error: object}` if the handler thew an error. The error is serialized.
+ *   - `{result: any}` if the handler invoked successfully.
+ *   - `{error: object}` if the handler thew an error. The error is serialized.
  * @param {...*} extraArgs Additional arguments which are passed to the `handler` function.
  * @returns {boolean} `true` if the function is invoked asynchronously, `false` otherwise.
  */
@@ -413,7 +413,7 @@ class EventDispatcher {
     /**
      * Adds a single event listener to a specific event.
      * @param {string} eventName The string representing the event's name.
-     * @param {function} callback The event listener callback to add.
+     * @param {Function} callback The event listener callback to add.
      */
     on(eventName, callback) {
         let callbacks = this._eventMap.get(eventName);
@@ -427,7 +427,7 @@ class EventDispatcher {
     /**
      * Removes a single event listener from a specific event.
      * @param {string} eventName The string representing the event's name.
-     * @param {function} callback The event listener callback to add.
+     * @param {Function} callback The event listener callback to add.
      * @returns {boolean} `true` if the callback was removed, `false` otherwise.
      */
     off(eventName, callback) {
@@ -482,6 +482,7 @@ class EventListenerCollection {
      * @param {string} type The type of event listener, which can be 'addEventListener', 'addListener', or 'on'.
      * @param {object} object The object to add the event listener to.
      * @param {...*} args The argument array passed to the object's event listener adding function.
+     * @returns {void}
      * @throws An error if type is not an expected value.
      */
     addGeneric(type, object, ...args) {
@@ -539,8 +540,6 @@ class EventListenerCollection {
                 case 'off':
                     object.off(...args);
                     break;
-                default:
-                    throw new Error(`Unknown remove function: ${removeFunctionName}`);
             }
         }
         this._eventListeners = [];
diff --git a/ext/js/data/anki-util.js b/ext/js/data/anki-util.js
index faccbc84..bb375230 100644
--- a/ext/js/data/anki-util.js
+++ b/ext/js/data/anki-util.js
@@ -22,8 +22,8 @@ class AnkiUtil {
     /**
      * Gets the root deck name of a full deck name. If the deck is a root deck,
      * the same name is returned. Nested decks are separated using '::'.
-     * @param deckName A string of the deck name.
-     * @returns A string corresponding to the name of the root deck.
+     * @param {string} deckName A string of the deck name.
+     * @returns {string} A string corresponding to the name of the root deck.
      */
     static getRootDeckName(deckName) {
         const index = deckName.indexOf('::');
@@ -32,8 +32,8 @@ class AnkiUtil {
 
     /**
      * Checks whether or not any marker is contained in a string.
-     * @param string A string to check.
-     * @return `true` if the text contains an Anki field marker, `false` otherwise.
+     * @param {string} string A string to check.
+     * @returns {boolean} `true` if the text contains an Anki field marker, `false` otherwise.
      */
     static stringContainsAnyFieldMarker(string) {
         const result = this._markerPattern.test(string);
@@ -43,8 +43,8 @@ class AnkiUtil {
 
     /**
      * Gets a list of all markers that are contained in a string.
-     * @param string A string to check.
-     * @return An array of marker strings.
+     * @param {string} string A string to check.
+     * @returns {string[]} An array of marker strings.
      */
     static getFieldMarkers(string) {
         const pattern = this._markerPattern;
@@ -58,25 +58,9 @@ class AnkiUtil {
     }
 
     /**
-     * Checks whether an object of key-value pairs has a value which contains a specific marker.
-     * @param fieldsObject An object with key-value pairs, where the value corresponds to the field value.
-     * @param marker The marker string to check for, excluding brackets.
-     * @returns `true` if any of the fields contains the marker, `false` otherwise.
-     */
-    static fieldsObjectContainsMarker(fieldsObject, marker) {
-        marker = `{${marker}}`;
-        for (const [, fieldValue] of fieldsObject) {
-            if (fieldValue.includes(marker)) {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    /**
      * Returns a regular expression which can be used to find markers in a string.
-     * @param global Whether or not the regular expression should have the global flag.
-     * @returns A new `RegExp` instance.
+     * @param {boolean} global Whether or not the regular expression should have the global flag.
+     * @returns {RegExp} A new `RegExp` instance.
      */
     static cloneFieldMarkerPattern(global) {
         return new RegExp(this._markerPattern.source, global ? 'g' : '');
@@ -84,8 +68,8 @@ class AnkiUtil {
 
     /**
      * Checks whether or not a note object is valid.
-     * @param note A note object to check.
-     * @return `true` if the note is valid, `false` otherwise.
+     * @param {*} note A note object to check.
+     * @returns {boolean} `true` if the note is valid, `false` otherwise.
      */
     static isNoteDataValid(note) {
         if (!isObject(note)) { return false; }
diff --git a/ext/js/data/sandbox/anki-note-data-creator.js b/ext/js/data/sandbox/anki-note-data-creator.js
index 96f97896..e1c32193 100644
--- a/ext/js/data/sandbox/anki-note-data-creator.js
+++ b/ext/js/data/sandbox/anki-note-data-creator.js
@@ -26,7 +26,7 @@
 class AnkiNoteDataCreator {
     /**
      * Creates a new instance.
-     * @param japaneseUtil An instance of `JapaneseUtil`.
+     * @param {JapaneseUtil} japaneseUtil An instance of `JapaneseUtil`.
      */
     constructor(japaneseUtil) {
         this._japaneseUtil = japaneseUtil;
@@ -34,8 +34,16 @@ class AnkiNoteDataCreator {
 
     /**
      * Creates a compatibility representation of the specified data.
-     * @param marker The marker that is being used for template rendering.
-     * @returns An object used for rendering Anki templates.
+     * @param {string} marker The marker that is being used for template rendering.
+     * @param {object} details Information which is used to generate the data.
+     * @param {Translation.DictionaryEntry} details.dictionaryEntry The dictionary entry.
+     * @param {string} details.resultOutputMode The result output mode.
+     * @param {string} details.mode The mode being used to generate the Anki data.
+     * @param {string} details.glossaryLayoutMode The glossary layout mode.
+     * @param {boolean} details.compactTags Whether or not compact tags mode is enabled.
+     * @param {{documentTitle: string, query: string, fullQuery: string}} details.context Contextual information about the source of the dictionary entry.
+     * @param {object} details.media Media data.
+     * @returns {object} An object used for rendering Anki templates.
      */
     create(marker, {
         dictionaryEntry,
@@ -83,8 +91,8 @@ class AnkiNoteDataCreator {
 
     /**
      * Creates a deferred-evaluation value.
-     * @param getter The function to invoke to get the return value.
-     * @returns An object which can be passed into `getCachedValue`.
+     * @param {Function} getter The function to invoke to get the return value.
+     * @returns {{getter: Function, hasValue: false, value: undefined}} An object which can be passed into `getCachedValue`.
      */
     createCachedValue(getter) {
         return {getter, hasValue: false, value: void 0};
@@ -92,8 +100,8 @@ class AnkiNoteDataCreator {
 
     /**
      * Gets the value of a cached object.
-     * @param item An object that was returned from `createCachedValue`.
-     * @returns The result of evaluating the getter, which is cached after the first invocation.
+     * @param {{getter: Function, hasValue: boolean, value: *}} item An object that was returned from `createCachedValue`.
+     * @returns {*} The result of evaluating the getter, which is cached after the first invocation.
      */
     getCachedValue(item) {
         if (item.hasValue) { return item.value; }
diff --git a/ext/js/data/sandbox/string-util.js b/ext/js/data/sandbox/string-util.js
index 5c395be7..de6933cd 100644
--- a/ext/js/data/sandbox/string-util.js
+++ b/ext/js/data/sandbox/string-util.js
@@ -21,8 +21,8 @@
 class StringUtil {
     /**
      * Decodes the contents of an ArrayBuffer using UTF8.
-     * @param arrayBuffer The input ArrayBuffer.
-     * @returns A UTF8-decoded string.
+     * @param {ArrayBuffer} arrayBuffer The input ArrayBuffer.
+     * @returns {string} A UTF8-decoded string.
      */
     static arrayBufferUtf8Decode(arrayBuffer) {
         try {
@@ -34,8 +34,8 @@ class StringUtil {
 
     /**
      * Converts the contents of an ArrayBuffer to a base64 string.
-     * @param arrayBuffer The input ArrayBuffer.
-     * @returns A base64 string representing the binary content.
+     * @param {ArrayBuffer} arrayBuffer The input ArrayBuffer.
+     * @returns {string} A base64 string representing the binary content.
      */
     static arrayBufferToBase64(arrayBuffer) {
         return btoa(this.arrayBufferToBinaryString(arrayBuffer));
@@ -43,8 +43,8 @@ class StringUtil {
 
     /**
      * Converts the contents of an ArrayBuffer to a binary string.
-     * @param arrayBuffer The input ArrayBuffer.
-     * @returns A string representing the binary content.
+     * @param {ArrayBuffer} arrayBuffer The input ArrayBuffer.
+     * @returns {string} A string representing the binary content.
      */
     static arrayBufferToBinaryString(arrayBuffer) {
         const bytes = new Uint8Array(arrayBuffer);
@@ -61,8 +61,8 @@ class StringUtil {
 
     /**
      * Converts a base64 string to an ArrayBuffer.
-     * @param content The binary content string encoded in base64.
-     * @returns A new `ArrayBuffer` object corresponding to the specified content.
+     * @param {string} content The binary content string encoded in base64.
+     * @returns {ArrayBuffer} A new `ArrayBuffer` object corresponding to the specified content.
      */
     static base64ToArrayBuffer(content) {
         const binaryContent = atob(content);
diff --git a/ext/js/display/display.js b/ext/js/display/display.js
index 82364233..aad54e1c 100644
--- a/ext/js/display/display.js
+++ b/ext/js/display/display.js
@@ -39,6 +39,49 @@ class Display extends EventDispatcher {
     /**
      * Information about how popup content should be shown, specifically related to the inner popup content.
      * @typedef {object} ContentDetails
+     * @property {boolean} focus Whether or not the frame should be `focus()`'d.
+     * @property {HistoryParams} params An object containing key-value pairs representing the URL search params.
+     * @property {?HistoryState} state The semi-persistent state assigned to the navigation entry.
+     * @property {?HistoryContent} content The non-persistent content assigned to the navigation entry.
+     * @property {'clear'|'overwrite'|'new'} historyMode How the navigation history should be modified.
+     */
+
+    /**
+     * An object containing key-value pairs representing the URL search params.
+     * @typedef {object} HistoryParams
+     * @property {'terms'|'kanji'|'unloaded'|'clear'} [type] The type of content that is being shown.
+     * @property {string} [query] The search query.
+     * @property {'on'|'off'} [wildcards] Whether or not wildcards can be used for the search query.
+     * @property {string} [offset] The start position of the `query` string as an index into the `full` query string.
+     * @property {string} [full] The full search text. If absent, `query` is the full search text.
+     * @property {'true'|'false'} [full-visible] Whether or not the full search query should be forced to be visible.
+     * @property {'true'|'false'} [lookup] Whether or not the query should be looked up. If it is not looked up,
+     *   the content should be provided.
+     */
+
+    /**
+     * The semi-persistent state assigned to the navigation entry.
+     * @typedef {object} HistoryState
+     * @property {'queryParser'} [cause] What was the cause of the navigation.
+     * @property {object} [sentence] The sentence context.
+     * @property {string} sentence.text The full string.
+     * @property {number} sentence.offset The offset from the start of `text` to the full search query.
+     * @property {number} [focusEntry] The index of the dictionary entry to focus.
+     * @property {number} [scrollX] The horizontal scroll position.
+     * @property {number} [scrollY] The vertical scroll position.
+     * @property {object} [optionsContext] The options context which should be used for lookups.
+     * @property {string} [url] The originating URL of the content.
+     * @property {string} [documentTitle] The originating document title of the content.
+     */
+
+    /**
+     * The non-persistent content assigned to the navigation entry.
+     * @typedef {object} HistoryContent
+     * @property {boolean} [animate] Whether or not any CSS animations should occur.
+     * @property {object[]} [dictionaryEntries] An array of dictionary entries to display as content.
+     * @property {object} [contentOrigin] The identifying information for the frame the content originated from.
+     * @property {number} [contentOrigin.tabId] The tab id.
+     * @property {number} [contentOrigin.frameId] The frame id within the tab.
      */
 
     constructor(tabId, frameId, pageType, japaneseUtil, documentFocusController, hotkeyHandler) {
@@ -348,7 +391,7 @@ class Display extends EventDispatcher {
 
     /**
      * Updates the content of the display.
-     * @param {ContentDetails} details
+     * @param {ContentDetails} details Information about the content to show.
      */
     setContent(details) {
         const {focus, params, state, content} = details;
diff --git a/ext/js/dom/document-util.js b/ext/js/dom/document-util.js
index 10d91551..f5cf194b 100644
--- a/ext/js/dom/document-util.js
+++ b/ext/js/dom/document-util.js
@@ -68,27 +68,27 @@ class DocumentUtil {
 
     /**
      * Extract a sentence from a document.
-     * @param source The text source object, either `TextSourceRange` or `TextSourceElement`.
-     * @param layoutAwareScan Whether or not layout-aware scan mode should be used.
-     * @param extent The length of the sentence to extract.
-     * @param terminateAtNewlines Whether or not a sentence should be terminated at newline characters.
-     * @param terminatorMap A mapping of characters that terminate a sentence.
+     * @param {TextSourceRange|TextSourceElement} source The text source object, either `TextSourceRange` or `TextSourceElement`.
+     * @param {boolean} layoutAwareScan Whether or not layout-aware scan mode should be used.
+     * @param {number} extent The length of the sentence to extract.
+     * @param {boolean} terminateAtNewlines Whether or not a sentence should be terminated at newline characters.
+     * @param {Map<string, *[]>} terminatorMap A mapping of characters that terminate a sentence.
      *   Format:
      *   ```js
      *   new Map([ [character: string, [includeCharacterAtStart: boolean, includeCharacterAtEnd: boolean]], ... ])
      *   ```
-     * @param forwardQuoteMap A mapping of quote characters that delimit a sentence.
+     * @param {Map<string, *[]>} forwardQuoteMap A mapping of quote characters that delimit a sentence.
      *   Format:
      *   ```js
      *   new Map([ [character: string, [otherCharacter: string, includeCharacterAtStart: boolean]], ... ])
      *   ```
-     * @param backwardQuoteMap A mapping of quote characters that delimit a sentence,
+     * @param {Map<string, *[]>} backwardQuoteMap A mapping of quote characters that delimit a sentence,
      *   which is the inverse of forwardQuoteMap.
      *   Format:
      *   ```js
      *   new Map([ [character: string, [otherCharacter: string, includeCharacterAtEnd: boolean]], ... ])
      *   ```
-     * @returns The sentence and the offset to the original source: `{sentence: string, offset: integer}`.
+     * @returns {{sentence: string, offset: number}} The sentence and the offset to the original source.
      */
     extractSentence(source, layoutAwareScan, extent, terminateAtNewlines, terminatorMap, forwardQuoteMap, backwardQuoteMap) {
         // Scan text
diff --git a/ext/js/dom/dom-text-scanner.js b/ext/js/dom/dom-text-scanner.js
index fff08825..83b16028 100644
--- a/ext/js/dom/dom-text-scanner.js
+++ b/ext/js/dom/dom-text-scanner.js
@@ -21,9 +21,12 @@
 class DOMTextScanner {
     /**
      * Creates a new instance of a DOMTextScanner.
-     * @param node The DOM Node to start at.
-     * @param offset The character offset in to start at when node is a text node.
+     * @param {Node} node The DOM Node to start at.
+     * @param {number} offset The character offset in to start at when node is a text node.
      *   Use 0 for non-text nodes.
+     * @param {boolean} forcePreserveWhitespace Whether or not whitespace should be forced to be preserved,
+     *   regardless of CSS styling.
+     * @param {boolean} generateLayoutContent Whether or not newlines should be added based on CSS styling.
      */
     constructor(node, offset, forcePreserveWhitespace=false, generateLayoutContent=true) {
         const ruby = DOMTextScanner.getParentRubyElement(node);
@@ -393,6 +396,7 @@ class DOMTextScanner {
 
     /**
      * Gets seek information about an element.
+     * @param {Element} element The element to check.
      * @returns {{enterable: boolean, newlines: number}} The seek information.
      *   The `enterable` value indicates whether the content of this node should be entered.
      *   The `newlines` value corresponds to the number of newline characters that should be added.
@@ -443,6 +447,8 @@ class DOMTextScanner {
     /**
      * Gets attributes for the specified character.
      * @param {string} character A string containing a single character.
+     * @param {boolean} preserveNewlines Whether or not newlines should be preserved.
+     * @param {boolean} preserveWhitespace Whether or not whitespace should be preserved.
      * @returns {number} An integer representing the attributes of the character.
      *   0: Character should be ignored.
      *   1: Character is collapsible whitespace.
diff --git a/ext/js/dom/sandbox/css-style-applier.js b/ext/js/dom/sandbox/css-style-applier.js
index a6938d92..6c45f13e 100644
--- a/ext/js/dom/sandbox/css-style-applier.js
+++ b/ext/js/dom/sandbox/css-style-applier.js
@@ -36,8 +36,9 @@ class CssStyleApplier {
 
     /**
      * Creates a new instance of the class.
-     * @param styleDataUrl The local URL to the JSON file continaing the style rules.
+     * @param {string} styleDataUrl The local URL to the JSON file continaing the style rules.
      *   The style rules should be of the format:
+     *   ```
      *   [
      *     {
      *       selectors: [(selector:string)...],
@@ -46,6 +47,7 @@ class CssStyleApplier {
      *       ]
      *     }...
      *   ]
+     *   ```
      */
     constructor(styleDataUrl) {
         this._styleDataUrl = styleDataUrl;
@@ -84,7 +86,7 @@ class CssStyleApplier {
     /**
      * Applies CSS styles directly to the "style" attribute using the "class" attribute.
      * This only works for elements with a single class.
-     * @param elements An iterable collection of HTMLElement objects.
+     * @param {Iterable<HTMLElement>} elements An iterable collection of HTMLElement objects.
      */
     applyClassStyles(elements) {
         const elementStyles = [];
diff --git a/ext/js/dom/selector-observer.js b/ext/js/dom/selector-observer.js
index c2065103..071c3971 100644
--- a/ext/js/dom/selector-observer.js
+++ b/ext/js/dom/selector-observer.js
@@ -20,18 +20,40 @@
  */
 class SelectorObserver {
     /**
+     * @function OnAddedCallback
+     * @param {Element} element The element which was added.
+     * @returns {*} Custom data which is assigned to element and passed to callbacks.
+     */
+
+    /**
+     * @function OnRemovedCallback
+     * @param {Element} element The element which was removed.
+     * @param {*} data The custom data corresponding to the element.
+     */
+
+    /**
+     * @function OnChildrenUpdatedCallback
+     * @param {Element} element The element which had its children updated.
+     * @param {*} data The custom data corresponding to the element.
+     */
+
+    /**
+     * @function IsStaleCallback
+     * @param {Element} element The element which had its children updated.
+     * @param {*} data The custom data corresponding to the element.
+     * @returns {boolean} Whether or not the data is stale for the element.
+     */
+
+    /**
      * Creates a new instance.
-     * @param selector A string CSS selector used to find elements.
-     * @param ignoreSelector A string CSS selector used to filter elements, or null for no filtering.
-     * @param onAdded A function which is invoked for each element that is added that matches the selector.
-     *   The signature is (element) => data.
-     * @param onRemoved A function which is invoked for each element that is removed, or null.
-     *   The signature is (element, data) => void.
-     * @param onChildrenUpdated A function which is invoked for each element which has its children updated, or null.
-     *   The signature is (element, data) => void.
-     * @param isStale A function which checks if the data is stale for a given element, or null.
+     * @param {object} details The configuration for the object.
+     * @param {string} details.selector A string CSS selector used to find elements.
+     * @param {?string} details.ignoreSelector A string CSS selector used to filter elements, or `null` for no filtering.
+     * @param {OnAddedCallback} details.onAdded A function which is invoked for each element that is added that matches the selector.
+     * @param {?OnRemovedCallback} details.onRemoved A function which is invoked for each element that is removed, or `null`.
+     * @param {?OnChildrenUpdatedCallback} details.onChildrenUpdated A function which is invoked for each element which has its children updated, or `null`.
+     * @param {?IsStaleCallback} details.isStale A function which checks if the data is stale for a given element, or `null`.
      *   If the element is stale, it will be removed and potentially re-added.
-     *   The signature is (element, data) => bool.
      */
     constructor({selector, ignoreSelector=null, onAdded=null, onRemoved=null, onChildrenUpdated=null, isStale=null}) {
         this._selector = selector;
@@ -49,7 +71,7 @@ class SelectorObserver {
 
     /**
      * Returns whether or not an element is currently being observed.
-     * @returns True if an element is being observed, false otherwise.
+     * @returns {boolean} `true` if an element is being observed, `false` otherwise.
      */
     get isObserving() {
         return this._observingElement !== null;
@@ -57,10 +79,10 @@ class SelectorObserver {
 
     /**
      * Starts DOM mutation observing the target element.
-     * @param element The element to observe changes in.
-     * @param attributes A boolean for whether or not attribute changes should be observed.
-     * @throws An error if element is null.
-     * @throws An error if an element is already being observed.
+     * @param {Element} element The element to observe changes in.
+     * @param {boolean} [attributes] A boolean for whether or not attribute changes should be observed.
+     * @throws {Error} An error if element is null.
+     * @throws {Error} An error if an element is already being observed.
      */
     observe(element, attributes=false) {
         if (element === null) {
diff --git a/ext/js/general/cache-map.js b/ext/js/general/cache-map.js
index f993cc26..fccb7cdd 100644
--- a/ext/js/general/cache-map.js
+++ b/ext/js/general/cache-map.js
@@ -21,7 +21,7 @@
 class CacheMap {
     /**
      * Creates a new CacheMap.
-     * @param maxSize The maximum number of entries able to be stored in the cache.
+     * @param {number} maxSize The maximum number of entries able to be stored in the cache.
      */
     constructor(maxSize) {
         if (!(
@@ -42,6 +42,7 @@ class CacheMap {
 
     /**
      * Returns the number of items in the cache.
+     * @type {number}
      */
     get size() {
         return this._map.size;
@@ -49,6 +50,7 @@ class CacheMap {
 
     /**
      * Returns the maximum number of items that can be added to the cache.
+     * @type {number}
      */
     get maxSize() {
         return this._maxSize;
@@ -56,8 +58,8 @@ class CacheMap {
 
     /**
      * Returns whether or not an element exists at the given key.
-     * @param key The key of the element.
-     * @returns `true` if an element with the specified key exists, `false` otherwise.
+     * @param {*} key The key of the element.
+     * @returns {boolean} `true` if an element with the specified key exists, `false` otherwise.
      */
     has(key) {
         return this._map.has(key);
@@ -65,8 +67,8 @@ class CacheMap {
 
     /**
      * Gets an element at the given key, if it exists. Otherwise, returns undefined.
-     * @param key The key of the element.
-     * @returns The existing value at the key, if any; `undefined` otherwise.
+     * @param {*} key The key of the element.
+     * @returns {*} The existing value at the key, if any; `undefined` otherwise.
      */
     get(key) {
         const node = this._map.get(key);
@@ -77,8 +79,8 @@ class CacheMap {
 
     /**
      * Sets a value at a given key.
-     * @param key The key of the element.
-     * @param value The value to store in the cache.
+     * @param {*} key The key of the element.
+     * @param {*} value The value to store in the cache.
      */
     set(key, value) {
         let node = this._map.get(key);
diff --git a/ext/js/general/object-property-accessor.js b/ext/js/general/object-property-accessor.js
index 516ad72f..ea410ac3 100644
--- a/ext/js/general/object-property-accessor.js
+++ b/ext/js/general/object-property-accessor.js
@@ -21,8 +21,7 @@
 class ObjectPropertyAccessor {
     /**
      * Create a new accessor for a specific object.
-     * @param target The object which the getter and mutation methods are applied to.
-     * @returns A new ObjectPropertyAccessor instance.
+     * @param {object} target The object which the getter and mutation methods are applied to.
      */
     constructor(target) {
         this._target = target;
@@ -30,11 +29,11 @@ class ObjectPropertyAccessor {
 
     /**
      * Gets the value at the specified path.
-     * @param pathArray The path to the property on the target object.
-     * @param pathLength How many parts of the pathArray to use.
+     * @param {(string|number)[]} pathArray The path to the property on the target object.
+     * @param {number} [pathLength] How many parts of the pathArray to use.
      *   This parameter is optional and defaults to the length of pathArray.
-     * @returns The value found at the path.
-     * @throws An error is thrown if pathArray is not valid for the target object.
+     * @returns {*} The value found at the path.
+     * @throws {Error} An error is thrown if pathArray is not valid for the target object.
      */
     get(pathArray, pathLength) {
         let target = this._target;
@@ -51,9 +50,9 @@ class ObjectPropertyAccessor {
 
     /**
      * Sets the value at the specified path.
-     * @param pathArray The path to the property on the target object.
-     * @param value The value to assign to the property.
-     * @throws An error is thrown if pathArray is not valid for the target object.
+     * @param {(string|number)[]} pathArray The path to the property on the target object.
+     * @param {*} value The value to assign to the property.
+     * @throws {Error} An error is thrown if pathArray is not valid for the target object.
      */
     set(pathArray, value) {
         const ii = pathArray.length - 1;
@@ -70,8 +69,8 @@ class ObjectPropertyAccessor {
 
     /**
      * Deletes the property of the target object at the specified path.
-     * @param pathArray The path to the property on the target object.
-     * @throws An error is thrown if pathArray is not valid for the target object.
+     * @param {(string|number)[]}pathArray The path to the property on the target object.
+     * @throws {Error} An error is thrown if pathArray is not valid for the target object.
      */
     delete(pathArray) {
         const ii = pathArray.length - 1;
@@ -92,8 +91,8 @@ class ObjectPropertyAccessor {
 
     /**
      * Swaps two properties of an object or array.
-     * @param pathArray1 The path to the first property on the target object.
-     * @param pathArray2 The path to the second property on the target object.
+     * @param {(string|number)[]} pathArray1 The path to the first property on the target object.
+     * @param {(string|number)[]} pathArray2 The path to the second property on the target object.
      * @throws An error is thrown if pathArray1 or pathArray2 is not valid for the target object,
      *   or if the swap cannot be performed.
      */
@@ -129,8 +128,9 @@ class ObjectPropertyAccessor {
 
     /**
      * Converts a path string to a path array.
-     * @param pathArray The path array to convert.
-     * @returns A string representation of pathArray.
+     * @param {(string|number)[]} pathArray The path array to convert.
+     * @returns {string} A string representation of `pathArray`.
+     * @throws {Error} An error is thrown if any item of `pathArray` is not a string or an integer.
      */
     static getPathString(pathArray) {
         const regexShort = /^[a-zA-Z_][a-zA-Z0-9_]*$/;
@@ -166,8 +166,9 @@ class ObjectPropertyAccessor {
     /**
      * Converts a path array to a path string. For the most part, the format of this string
      * matches Javascript's notation for property access.
-     * @param pathString The path string to convert.
-     * @returns An array representation of pathString.
+     * @param {string} pathString The path string to convert.
+     * @returns {(string | number)[]} An array representation of `pathString`.
+     * @throws {Error} An error is thrown if `pathString` is malformed.
      */
     static getPathArray(pathString) {
         const pathArray = [];
@@ -286,11 +287,11 @@ class ObjectPropertyAccessor {
 
     /**
      * Checks whether an object or array has the specified property.
-     * @param object The object to test.
-     * @param property The property to check for existence.
+     * @param {*} object The object to test.
+     * @param {string|number} property The property to check for existence.
      *   This value should be a string if the object is a non-array object.
      *   For arrays, it should be an integer.
-     * @returns true if the property exists, otherwise false.
+     * @returns {boolean} `true` if the property exists, otherwise `false`.
      */
     static hasProperty(object, property) {
         switch (typeof property) {
@@ -315,9 +316,9 @@ class ObjectPropertyAccessor {
 
     /**
      * Checks whether a property is valid for the given object
-     * @param object The object to test.
-     * @param property The property to check for existence.
-     * @returns true if the property is correct for the given object type, otherwise false.
+     * @param {object} object The object to test.
+     * @param {string|number} property The property to check for existence.
+     * @returns {boolean} `true` if the property is correct for the given object type, otherwise `false`.
      *   For arrays, this means that the property should be a positive integer.
      *   For non-array objects, the property should be a string.
      */
diff --git a/ext/js/general/regex-util.js b/ext/js/general/regex-util.js
index d74a2f1e..6fa1a220 100644
--- a/ext/js/general/regex-util.js
+++ b/ext/js/general/regex-util.js
@@ -22,12 +22,12 @@ class RegexUtil {
     /**
      * Applies string.replace using a regular expression and replacement string as arguments.
      * A source map of the changes is also maintained.
-     * @param text A string of the text to replace.
-     * @param sourceMap An instance of `TextSourceMap` which corresponds to `text`.
-     * @param pattern A regular expression to use as the replacement.
-     * @param replacement A replacement string that follows the format of the standard
+     * @param {string} text A string of the text to replace.
+     * @param {TextSourceMap} sourceMap An instance of `TextSourceMap` which corresponds to `text`.
+     * @param {RegExp} pattern A regular expression to use as the replacement.
+     * @param {string} replacement A replacement string that follows the format of the standard
      *   JavaScript regular expression replacement string.
-     * @return A new string with the pattern replacements applied and the source map updated.
+     * @returns {string} A new string with the pattern replacements applied and the source map updated.
      */
     static applyTextReplacement(text, sourceMap, pattern, replacement) {
         const isGlobal = pattern.global;
@@ -57,10 +57,10 @@ class RegexUtil {
 
     /**
      * Applies the replacement string for a given regular expression match.
-     * @param replacement The replacement string that follows the format of the standard
+     * @param {string} replacement The replacement string that follows the format of the standard
      *   JavaScript regular expression replacement string.
-     * @param match A match object returned from RegExp.match.
-     * @return A new string with the pattern replacement applied.
+     * @param {object} match A match object returned from RegExp.match.
+     * @returns {string} A new string with the pattern replacement applied.
      */
     static applyMatchReplacement(replacement, match) {
         const pattern = this._matchReplacementPattern;
diff --git a/ext/js/input/hotkey-handler.js b/ext/js/input/hotkey-handler.js
index 33a449e3..dc0f6d3e 100644
--- a/ext/js/input/hotkey-handler.js
+++ b/ext/js/input/hotkey-handler.js
@@ -24,6 +24,16 @@
  */
 class HotkeyHandler extends EventDispatcher {
     /**
+     * Information describing a hotkey.
+     * @typedef {object} HotkeyDefinition
+     * @property {string} action A string indicating which action to perform.
+     * @property {string} key A keyboard key code indicating which key needs to be pressed.
+     * @property {string[]} modifiers An array of keyboard modifiers which also need to be pressed. Supports: `'alt', 'ctrl', 'shift', 'meta'`.
+     * @property {string[]} scopes An array of scopes for which the hotkey is valid. If this array does not contain `this.scope`, the hotkey will not be registered.
+     * @property {boolean} enabled A boolean indicating whether the hotkey is currently enabled.
+     */
+
+    /**
      * Creates a new instance of the class.
      */
     constructor() {
@@ -49,7 +59,7 @@ class HotkeyHandler extends EventDispatcher {
 
     /**
      * Registers a set of actions that this hotkey handler supports.
-     * @param actions An array of `[name, handler]` entries, where `name` is a string and `handler` is a function.
+     * @param {*[][]} actions An array of `[name, handler]` entries, where `name` is a string and `handler` is a function.
      */
     registerActions(actions) {
         for (const [name, handler] of actions) {
@@ -59,13 +69,8 @@ class HotkeyHandler extends EventDispatcher {
 
     /**
      * Registers a set of hotkeys for a given scope.
-     * @param scope The scope that the hotkey definitions must be for in order to be activated.
-     * @param hotkeys An array of hotkey definitions of the format `{action, key, modifiers, scopes, enabled}`.
-     * * `action` - a string indicating which action to perform.
-     * * `key` - a keyboard key code indicating which key needs to be pressed.
-     * * `modifiers` - an array of keyboard modifiers which also need to be pressed. Supports: `'alt', 'ctrl', 'shift', 'meta'`.
-     * * `scopes` - an array of scopes for which the hotkey is valid. If this array does not contain `this.scope`, the hotkey will not be registered.
-     * * `enabled` - a boolean indicating whether the hotkey is currently enabled.
+     * @param {string} scope The scope that the hotkey definitions must be for in order to be activated.
+     * @param {HotkeyDefinition[]} hotkeys An array of hotkey definitions.
      */
     registerHotkeys(scope, hotkeys) {
         let registrations = this._hotkeyRegistrations.get(scope);
@@ -79,6 +84,7 @@ class HotkeyHandler extends EventDispatcher {
 
     /**
      * Removes all registered hotkeys for a given scope.
+     * @param {string} scope The scope that the hotkey definitions were registered in.
      */
     clearHotkeys(scope) {
         const registrations = this._hotkeyRegistrations.get(scope);
@@ -91,7 +97,8 @@ class HotkeyHandler extends EventDispatcher {
     /**
      * Assigns a set of hotkeys for a given scope. This is an optimized shorthand for calling
      * `clearHotkeys`, then calling `registerHotkeys`.
-     * @see registerHotkeys for argument information.
+     * @param {string} scope The scope that the hotkey definitions must be for in order to be activated.
+     * @param {HotkeyDefinition[]} hotkeys An array of hotkey definitions.
      */
     setHotkeys(scope, hotkeys) {
         let registrations = this._hotkeyRegistrations.get(scope);
@@ -107,8 +114,9 @@ class HotkeyHandler extends EventDispatcher {
 
     /**
      * Adds a single event listener to a specific event.
-     * @param eventName The string representing the event's name.
-     * @param callback The event listener callback to add.
+     * @param {string} eventName The string representing the event's name.
+     * @param {Function} callback The event listener callback to add.
+     * @returns {void}
      */
     on(eventName, callback) {
         const result = super.on(eventName, callback);
@@ -119,9 +127,9 @@ class HotkeyHandler extends EventDispatcher {
 
     /**
      * Removes a single event listener from a specific event.
-     * @param eventName The string representing the event's name.
-     * @param callback The event listener callback to add.
-     * @returns `true` if the callback was removed, `false` otherwise.
+     * @param {string} eventName The string representing the event's name.
+     * @param {Function} callback The event listener callback to add.
+     * @returns {boolean} `true` if the callback was removed, `false` otherwise.
      */
     off(eventName, callback) {
         const result = super.off(eventName, callback);
@@ -132,9 +140,9 @@ class HotkeyHandler extends EventDispatcher {
 
     /**
      * Attempts to simulate an action for a given combination of key and modifiers.
-     * @param key A keyboard key code indicating which key needs to be pressed.
-     * @param modifiers An array of keyboard modifiers which also need to be pressed. Supports: `'alt', 'ctrl', 'shift', 'meta'`.
-     * @returns `true` if an action was performed, `false` otherwise.
+     * @param {string} key A keyboard key code indicating which key needs to be pressed.
+     * @param {string[]} modifiers An array of keyboard modifiers which also need to be pressed. Supports: `'alt', 'ctrl', 'shift', 'meta'`.
+     * @returns {boolean} `true` if an action was performed, `false` otherwise.
      */
     simulate(key, modifiers) {
         const hotkeyInfo = this._hotkeys.get(key);
diff --git a/ext/js/input/hotkey-util.js b/ext/js/input/hotkey-util.js
index 4dd9447a..35802106 100644
--- a/ext/js/input/hotkey-util.js
+++ b/ext/js/input/hotkey-util.js
@@ -21,6 +21,7 @@
 class HotkeyUtil {
     /**
      * Creates a new instance.
+     * @param {?string} os The operating system for this instance.
      */
     constructor(os=null) {
         this._os = os;
@@ -41,6 +42,7 @@ class HotkeyUtil {
     /**
      * Gets the operating system for this instance.
      * The operating system is used to display system-localized modifier key names.
+     * @type {?string}
      */
     get os() {
         return this._os;
@@ -48,7 +50,7 @@ class HotkeyUtil {
 
     /**
      * Sets the operating system for this instance.
-     * @param value The value to assign.
+     * @param {?string} value The value to assign.
      *   Valid values are: win, mac, linux, openbsd, cros, android.
      */
     set os(value) {
@@ -59,10 +61,10 @@ class HotkeyUtil {
 
     /**
      * Gets a display string for a key and a set of modifiers.
-     * @param key The key code string, or `null` for no key.
-     * @param modifiers An array of modifiers.
+     * @param {?string} key The key code string, or `null` for no key.
+     * @param {string[]} modifiers An array of modifiers.
      *   Valid values are: ctrl, alt, shift, meta, or mouseN, where N is an integer.
-     * @returns A user-friendly string for the combination of key and modifiers.
+     * @returns {string} A user-friendly string for the combination of key and modifiers.
      */
     getInputDisplayValue(key, modifiers) {
         const separator = this._inputSeparator;
@@ -85,9 +87,9 @@ class HotkeyUtil {
 
     /**
      * Gets a display string for a single modifier.
-     * @param modifier A string representing a modifier.
+     * @param {string} modifier A string representing a modifier.
      *   Valid values are: ctrl, alt, shift, meta, or mouseN, where N is an integer.
-     * @returns A user-friendly string for the modifier.
+     * @returns {string} A user-friendly string for the modifier.
      */
     getModifierDisplayValue(modifier) {
         const match = this._mouseInputNamePattern.exec(modifier);
@@ -101,8 +103,8 @@ class HotkeyUtil {
 
     /**
      * Gets a display string for a key.
-     * @param key The key code string, or `null` for no key.
-     * @returns A user-friendly string for the combination of key and modifiers, or `null` if key was already `null`.
+     * @param {?string} key The key code string, or `null` for no key.
+     * @returns {?string} A user-friendly string for the combination of key and modifiers, or `null` if key was already `null`.
      */
     getKeyDisplayValue(key) {
         if (typeof key === 'string' && key.length === 4 && key.startsWith('Key')) {
@@ -113,9 +115,9 @@ class HotkeyUtil {
 
     /**
      * Gets a display string for a single modifier.
-     * @param modifier A string representing a modifier.
+     * @param {string} modifier A string representing a modifier.
      *   Valid values are: ctrl, alt, shift, meta, or mouseN, where N is an integer.
-     * @returns `'mouse'` if the modifier represents a mouse button, `'key'` otherwise.
+     * @returns {'mouse'|'key'} `'mouse'` if the modifier represents a mouse button, `'key'` otherwise.
      */
     getModifierType(modifier) {
         return (this._mouseInputNamePattern.test(modifier) ? 'mouse' : 'key');
@@ -123,8 +125,8 @@ class HotkeyUtil {
 
     /**
      * Converts an extension command string into a standard input.
-     * @param command An extension command string.
-     * @returns An object `{key, modifiers}`, where key is a string (or `null`) representing the key, and modifiers is an array of modifier keys.
+     * @param {string} command An extension command string.
+     * @returns {{key: ?string, modifiers: string[]}} An object `{key, modifiers}`, where key is a string (or `null`) representing the key, and modifiers is an array of modifier keys.
      */
     convertCommandToInput(command) {
         let key = null;
@@ -142,10 +144,10 @@ class HotkeyUtil {
 
     /**
      * Gets a command string for a specified input.
-     * @param key The key code string, or `null` for no key.
-     * @param modifiers An array of modifier keys.
+     * @param {?string} key The key code string, or `null` for no key.
+     * @param {string[]} modifiers An array of modifier keys.
      *   Valid values are: ctrl, alt, shift, meta.
-     * @returns An extension command string representing the input.
+     * @returns {string} An extension command string representing the input.
      */
     convertInputToCommand(key, modifiers) {
         const separator = '+';
@@ -168,9 +170,9 @@ class HotkeyUtil {
 
     /**
      * Sorts an array of modifiers.
-     * @param modifiers An array of modifiers.
+     * @param {string[]} modifiers An array of modifiers.
      *   Valid values are: ctrl, alt, shift, meta.
-     * @returns A sorted array of modifiers. The array instance is the same as the input array.
+     * @returns {string[]} A sorted array of modifiers. The array instance is the same as the input array.
      */
     sortModifiers(modifiers) {
         const pattern = this._mouseInputNamePattern;
diff --git a/ext/js/language/dictionary-importer-media-loader.js b/ext/js/language/dictionary-importer-media-loader.js
index 69a27f71..ce03ab20 100644
--- a/ext/js/language/dictionary-importer-media-loader.js
+++ b/ext/js/language/dictionary-importer-media-loader.js
@@ -21,9 +21,12 @@
 class DictionaryImporterMediaLoader {
     /**
      * Attempts to load an image using an ArrayBuffer and a media type to return details about it.
-     * @param content The binary content for the image, encoded as an ArrayBuffer.
-     * @param mediaType The media type for the image content.
-     * @returns A Promise which resolves with {content, width, height} on success, otherwise an error is thrown.
+     * @param {ArrayBuffer} content The binary content for the image, encoded as an ArrayBuffer.
+     * @param {string} mediaType The media type for the image content.
+     * @param {Transferable[]} [transfer] An optional array of data that should be transferred in `postMessage` calls.
+     *   When the resulting promise resolves, this array will contain the `content` object.
+     * @returns {Promise<{content: ArrayBuffer, width: number, height: number}>} Details about the requested image content.
+     * @throws {Error} An error can be thrown if the image fails to load.
      */
     getImageDetails(content, mediaType, transfer) {
         return new Promise((resolve, reject) => {
diff --git a/ext/js/language/dictionary-worker-media-loader.js b/ext/js/language/dictionary-worker-media-loader.js
index fc7ecd17..7e30b333 100644
--- a/ext/js/language/dictionary-worker-media-loader.js
+++ b/ext/js/language/dictionary-worker-media-loader.js
@@ -29,7 +29,7 @@ class DictionaryWorkerMediaLoader {
 
     /**
      * Handles a response message posted to the worker thread.
-     * @param params Details of the response.
+     * @param {{id: string, error: object|undefined, result: any|undefined}} params Details of the response.
      */
     handleMessage(params) {
         const {id} = params;
@@ -46,9 +46,10 @@ class DictionaryWorkerMediaLoader {
 
     /**
      * Attempts to load an image using an ArrayBuffer and a media type to return details about it.
-     * @param content The binary content for the image, encoded as an ArrayBuffer.
-     * @param mediaType The media type for the image content.
-     * @returns A Promise which resolves with {content, width, height} on success, otherwise an error is thrown.
+     * @param {ArrayBuffer} content The binary content for the image, encoded as an ArrayBuffer.
+     * @param {string} mediaType The media type for the image content.
+     * @returns {Promise<{content: ArrayBuffer, width: number, height: number}>} Details about the requested image content.
+     * @throws {Error} An error can be thrown if the image fails to load.
      */
     getImageDetails(content, mediaType) {
         return new Promise((resolve, reject) => {
diff --git a/ext/js/language/translator.js b/ext/js/language/translator.js
index fafd1bfb..73f27ff9 100644
--- a/ext/js/language/translator.js
+++ b/ext/js/language/translator.js
@@ -26,6 +26,16 @@
  */
 class Translator {
     /**
+     * Information about how popup content should be shown, specifically related to the outer popup frame.
+     * @typedef {object} TermFrequency
+     * @property {string} term The term.
+     * @property {string} reading The reading of the term.
+     * @property {string} dictionary The name of the dictionary that the term frequency originates from.
+     * @property {boolean} hasReading Whether or not a reading was specified.
+     * @property {number|string} frequency The frequency value for the term.
+     */
+
+    /**
      * Creates a new Translator instance.
      * @param {object} details The details for the class.
      * @param {JapaneseUtil} details.japaneseUtil An instance of JapaneseUtil.
diff --git a/ext/js/media/media-util.js b/ext/js/media/media-util.js
index 78668471..582b13a2 100644
--- a/ext/js/media/media-util.js
+++ b/ext/js/media/media-util.js
@@ -22,8 +22,8 @@ class MediaUtil {
     /**
      * Gets the file extension of a file path. URL search queries and hash
      * fragments are not handled.
-     * @param path The path to the file.
-     * @returns The file extension, including the '.', or an empty string
+     * @param {string} path The path to the file.
+     * @returns {string} The file extension, including the '.', or an empty string
      *   if there is no file extension.
      */
     static getFileNameExtension(path) {
@@ -33,9 +33,9 @@ class MediaUtil {
 
     /**
      * Gets an image file's media type using a file path.
-     * @param path The path to the file.
-     * @returns The media type string if it can be determined from the file path,
-     *   otherwise null.
+     * @param {string} path The path to the file.
+     * @returns {?string} The media type string if it can be determined from the file path,
+     *   otherwise `null`.
      */
     static getImageMediaTypeFromFileName(path) {
         switch (this.getFileNameExtension(path).toLowerCase()) {
@@ -70,9 +70,9 @@ class MediaUtil {
 
     /**
      * Gets the file extension for a corresponding media type.
-     * @param mediaType The media type to use.
-     * @returns A file extension including the dot for the media type,
-     *   otherwise null.
+     * @param {string} mediaType The media type to use.
+     * @returns {?string} A file extension including the dot for the media type,
+     *   otherwise `null`.
      */
     static getFileExtensionFromImageMediaType(mediaType) {
         switch (mediaType) {
@@ -101,9 +101,9 @@ class MediaUtil {
 
     /**
      * Gets the file extension for a corresponding media type.
-     * @param mediaType The media type to use.
-     * @returns A file extension including the dot for the media type,
-     *   otherwise null.
+     * @param {string} mediaType The media type to use.
+     * @returns {string} A file extension including the dot for the media type,
+     *   otherwise `null`.
      */
     static getFileExtensionFromAudioMediaType(mediaType) {
         switch (mediaType) {
diff --git a/ext/js/templates/sandbox/anki-template-renderer.js b/ext/js/templates/sandbox/anki-template-renderer.js
index 45dda06c..c5276f58 100644
--- a/ext/js/templates/sandbox/anki-template-renderer.js
+++ b/ext/js/templates/sandbox/anki-template-renderer.js
@@ -53,6 +53,7 @@ class AnkiTemplateRenderer {
 
     /**
      * Gets the generic TemplateRenderer instance.
+     * @type {TemplateRenderer}
      */
     get templateRenderer() {
         return this._templateRenderer;
diff --git a/ext/js/yomichan.js b/ext/js/yomichan.js
index 4ec9db9c..9bc9cc5f 100644
--- a/ext/js/yomichan.js
+++ b/ext/js/yomichan.js
@@ -150,16 +150,17 @@ class Yomichan extends EventDispatcher {
     /**
      * Checks whether or not a URL is an extension URL.
      * @param {string} url The URL to check.
-     * @returns true if the URL is an extension URL, false otherwise.
+     * @returns {boolean} `true` if the URL is an extension URL, `false` otherwise.
      */
     isExtensionUrl(url) {
         return this._extensionUrlBase !== null && url.startsWith(this._extensionUrlBase);
     }
 
     /**
-     * Runs chrome.runtime.sendMessage() with additional exception handling events.
-     * @param {...*} args The arguments to be passed to chrome.runtime.sendMessage().
-     * @returns {void} The result of the chrome.runtime.sendMessage() call.
+     * Runs `chrome.runtime.sendMessage()` with additional exception handling events.
+     * @param {...*} args The arguments to be passed to `chrome.runtime.sendMessage()`.
+     * @returns {void} The result of the `chrome.runtime.sendMessage()` call.
+     * @throws {Error} Errors thrown by `chrome.runtime.sendMessage()` are re-thrown.
      */
     sendMessage(...args) {
         try {
@@ -171,9 +172,10 @@ class Yomichan extends EventDispatcher {
     }
 
     /**
-     * Runs chrome.runtime.connect() with additional exception handling events.
-     * @param {...*} args The arguments to be passed to chrome.runtime.connect().
+     * Runs `chrome.runtime.connect()` with additional exception handling events.
+     * @param {...*} args The arguments to be passed to `chrome.runtime.connect()`.
      * @returns {Port} The resulting port.
+     * @throws {Error} Errors thrown by `chrome.runtime.connect()` are re-thrown.
      */
     connect(...args) {
         try {