JSDoc update (#1996)

* Update core.js docs to include types.

* Update docs

7 files changed, 593 insertions, 65 deletions

diff --git a/ext/js/app/frontend.js b/ext/js/app/frontend.js
index bbc0ff85..9fa6009b 100644
--- a/ext/js/app/frontend.js
+++ b/ext/js/app/frontend.js
@@ -21,7 +21,26 @@
  * TextSourceRange
  */
 
+/**
+ * This is the main class responsible for scanning and handling webpage content.
+ */
 class Frontend {
+    /**
+     * Creates a new instance.
+     * @param {object} details
+     * @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.
+     * @param {number} details.tabId The tab ID of the host tab.
+     * @param {number} details.frameId The frame ID of the host frame.
+     * @param {?string} details.parentPopupId The popup ID of the parent popup if one exists, otherwise null.
+     * @param {?number} details.parentFrameId The frame ID of the parent popup if one exists, otherwise null.
+     * @param {boolean} details.useProxyPopup Whether or not proxy popups should be used.
+     * @param {boolean} details.canUseWindowPopup Whether or not window popups can be used.
+     * @param {boolean} details.allowRootFramePopupProxy Whether or not popups can be hosted in the root frame.
+     * @param {boolean} details.childrenSupported Whether popups can create child popups or not.
+     * @param {HotkeyHandler} details.hotkeyHandler A HotkeyHandler instance.
+     */
     constructor({
         pageType,
         popupFactory,
@@ -83,18 +102,33 @@ class Frontend {
         ]);
     }
 
+    /**
+     * Get whether or not the text selection can be cleared.
+     * @type {boolean}
+     */
     get canClearSelection() {
         return this._textScanner.canClearSelection;
     }
 
+    /**
+     * Set whether or not the text selection can be cleared.
+     * @param {boolean} value The new value to assign.
+     */
     set canClearSelection(value) {
         this._textScanner.canClearSelection = value;
     }
 
+    /**
+     * Gets the popup instance.
+     * @type {Popup}
+     */
     get popup() {
         return this._popup;
     }
 
+    /**
+     * Prepares the instance for use.
+     */
     async prepare() {
         await this.updateOptions();
         try {
@@ -135,20 +169,35 @@ class Frontend {
         this._signalFrontendReady();
     }
 
+    /**
+     * Set whether or not the instance is disabled.
+     * @param {boolean} disabled Whether or not the instance is disabled.
+     */
     setDisabledOverride(disabled) {
         this._disabledOverride = disabled;
         this._updateTextScannerEnabled();
     }
 
+    /**
+     * Set or clear an override options context object.
+     * @param {?object} optionsContext An options context object to use as the override, or `null` to clear the override.
+     */
     setOptionsContextOverride(optionsContext) {
         this._optionsContextOverride = optionsContext;
     }
 
+    /**
+     * Performs a new search on a specific source.
+     * @param {TextSourceRange|TextSourceElement} textSource The text source to search.
+     */
     async setTextSource(textSource) {
         this._textScanner.setCurrentTextSource(null);
         await this._textScanner.search(textSource);
     }
 
+    /**
+     * Updates the internal options representation.
+     */
     async updateOptions() {
         try {
             await this._updateOptionsInternal();
@@ -159,6 +208,10 @@ class Frontend {
         }
     }
 
+    /**
+     * Waits for the previous `showContent` call to be completed.
+     * @returns {Promise} A promise which is resolved when the previous `showContent` call has completed.
+     */
     showContentCompleted() {
         return this._lastShowPromise;
     }
diff --git a/ext/js/app/popup-factory.js b/ext/js/app/popup-factory.js
index 096d145e..05ab1942 100644
--- a/ext/js/app/popup-factory.js
+++ b/ext/js/app/popup-factory.js
@@ -22,7 +22,14 @@
  * PopupWindow
  */
 
+/**
+ * A class which is used to generate and manage popups.
+ */
 class PopupFactory {
+    /**
+     * Creates a new instance.
+     * @param {number} frameId The frame ID of the host frame.
+     */
     constructor(frameId) {
         this._frameId = frameId;
         this._frameOffsetForwarder = new FrameOffsetForwarder(frameId);
@@ -32,6 +39,9 @@ class PopupFactory {
 
     // Public functions
 
+    /**
+     * Prepares the instance for use.
+     */
     prepare() {
         this._frameOffsetForwarder.prepare();
         yomichan.crossFrame.registerHandlers([
@@ -53,6 +63,16 @@ class PopupFactory {
         ]);
     }
 
+    /**
+     * Gets or creates a popup based on a set of parameters
+     * @param {object} details
+     * @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.
+     * @param {?number} [details.depth] A specific depth value to assign to the popup.
+     * @param {boolean} [details.popupWindow] Whether or not a separate popup window should be used, rather than an iframe.
+     * @param {boolean} [details.childrenSupported] Whether or not the popup is able to show child popups.
+     */
     async getOrCreatePopup({
         frameId=null,
         id=null,
@@ -148,6 +168,13 @@ class PopupFactory {
         }
     }
 
+    /**
+     * Force all popups to have a specific visibility value.
+     * @param {boolean} value Whether or not the popups should be visible.
+     * @param {number} priority The priority of the override.
+     * @returns {string} A token which can be passed to clearAllVisibleOverride.
+     * @throws An exception is thrown if any popup fails to have its visibiltiy overridden.
+     */
     async setAllVisibleOverride(value, priority) {
         const promises = [];
         const errors = [];
@@ -173,6 +200,11 @@ class PopupFactory {
         throw errors[0];
     }
 
+    /**
+     * Clears a visibility override that was generated by `setAllVisibleOverride`.
+     * @param {string} token The token returned from `setAllVisibleOverride`.
+     * @returns {boolean} `true` if the override existed and was removed, `false` otherwise.
+     */
     async clearAllVisibleOverride(token) {
         const results = this._allPopupVisibilityTokenMap.get(token);
         if (typeof results === 'undefined') { return false; }
diff --git a/ext/js/app/popup-proxy.js b/ext/js/app/popup-proxy.js
index c46821d5..d9e1af8d 100644
--- a/ext/js/app/popup-proxy.js
+++ b/ext/js/app/popup-proxy.js
@@ -15,7 +15,19 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/**
+ * This class is a proxy for a Popup that is hosted in a different frame.
+ * It effectively forwards all API calls to the underlying Popup.
+ */
 class PopupProxy extends EventDispatcher {
+    /**
+     * Creates a new instance.
+     * @param {object} details
+     * @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.
+     * @param {FrameOffsetForwarder} details.frameOffsetForwarder A `FrameOffsetForwarder` instance which is used to determine frame positioning.
+     */
     constructor({
         id,
         depth,
@@ -36,64 +48,137 @@ class PopupProxy extends EventDispatcher {
 
     // Public properties
 
+    /**
+     * The ID of the popup.
+     * @type {string}
+     */
     get id() {
         return this._id;
     }
 
+    /**
+     * The parent of the popup, which is always `null` for `PopupProxy` instances,
+     * since any potential parent popups are in a different frame.
+     * @type {Popup}
+     */
     get parent() {
         return null;
     }
 
+    /**
+     * Attempts to set the parent popup.
+     * @param {Popup} value
+     * @throws Throws an error, since this class doesn't support a direct parent.
+     */
     set parent(value) {
         throw new Error('Not supported on PopupProxy');
     }
 
+    /**
+     * The popup child popup, which is always null for `PopupProxy` instances,
+     * since any potential child popups are in a different frame.
+     * @type {Popup}
+     */
     get child() {
         return null;
     }
 
+    /**
+     * Attempts to set the child popup.
+     * @param {Popup} value
+     * @throws Throws an error, since this class doesn't support children.
+     */
     set child(value) {
         throw new Error('Not supported on PopupProxy');
     }
 
+    /**
+     * The depth of the popup.
+     * @type {numer}
+     */
     get depth() {
         return this._depth;
     }
 
+    /**
+     * Gets the content window of the frame. This value is null,
+     * since the window is hosted in a different frame.
+     * @type {Window}
+     */
     get frameContentWindow() {
         return null;
     }
 
+    /**
+     * Gets the DOM node that contains the frame.
+     * @type {Element}
+     */
     get container() {
         return null;
     }
 
+    /**
+     * Gets the ID of the frame.
+     * @type {number}
+     */
     get frameId() {
         return this._frameId;
     }
 
     // Public functions
 
+    /**
+     * Sets the options context for the popup.
+     * @param {object} optionsContext The options context object.
+     * @returns {Promise<void>}
+     */
     setOptionsContext(optionsContext, source) {
         return this._invokeSafe('setOptionsContext', {id: this._id, optionsContext, source});
     }
 
+    /**
+     * Hides the popup.
+     * @param {boolean} changeFocus Whether or not the parent popup or host frame should be focused.
+     * @returns {Promise<void>}
+     */
     hide(changeFocus) {
         return this._invokeSafe('hide', {id: this._id, changeFocus});
     }
 
+    /**
+     * Returns whether or not the popup is currently visible.
+     * @returns {Promise<boolean>} `true` if the popup is visible, `false` otherwise.
+     */
     isVisible() {
         return this._invokeSafe('isVisible', {id: this._id}, false);
     }
 
+    /**
+     * Force assigns the visibility of the popup.
+     * @param {boolean} value Whether or not the popup should be visible.
+     * @param {number} priority The priority of the override.
+     * @returns {Promise<string?>} A token used which can be passed to `clearVisibleOverride`,
+     *   or null if the override wasn't assigned.
+     */
     setVisibleOverride(value, priority) {
         return this._invokeSafe('setVisibleOverride', {id: this._id, value, priority}, null);
     }
 
+    /**
+     * Clears a visibility override that was generated by `setVisibleOverride`.
+     * @param {string} token The token returned from `setVisibleOverride`.
+     * @returns {Promise<boolean>} `true` if the override existed and was removed, `false` otherwise.
+     */
     clearVisibleOverride(token) {
         return this._invokeSafe('clearVisibleOverride', {id: this._id, token}, false);
     }
 
+    /**
+     * Checks whether a point is contained within the popup's rect.
+     * @param {number} x The x coordinate.
+     * @param {number} y The y coordinate.
+     * @returns {Promise<boolean>} `true` if the point is contained within the popup's rect, `false` otherwise.
+     */
     async containsPoint(x, y) {
         if (this._frameOffsetForwarder !== null) {
             await this._updateFrameOffset();
@@ -102,6 +187,12 @@ class PopupProxy extends EventDispatcher {
         return await this._invokeSafe('containsPoint', {id: this._id, x, y}, false);
     }
 
+    /**
+     * Shows and updates the positioning and content of the popup.
+     * @param {{optionsContext: object, elementRect: {x: number, y: number, width: number, height: number}, writingMode: string}} details Settings for the outer popup.
+     * @param {object} displayDetails The details parameter passed to `Display.setContent`; see that function for details.
+     * @returns {Promise<void>}
+     */
     async showContent(details, displayDetails) {
         const {elementRect} = details;
         if (typeof elementRect !== 'undefined' && this._frameOffsetForwarder !== null) {
@@ -111,38 +202,83 @@ class PopupProxy extends EventDispatcher {
         return await this._invokeSafe('showContent', {id: this._id, details, displayDetails});
     }
 
+    /**
+     * Sets the custom styles for the popup content.
+     * @param {string} css The CSS rules.
+     * @returns {Promise<void>}
+     */
     setCustomCss(css) {
         return this._invokeSafe('setCustomCss', {id: this._id, css});
     }
 
+    /**
+     * Stops the audio auto-play timer, if one has started.
+     * @returns {Promise<void>}
+     */
     clearAutoPlayTimer() {
         return this._invokeSafe('clearAutoPlayTimer', {id: this._id});
     }
 
+    /**
+     * Sets the scaling factor of the popup content.
+     * @param {number} scale The scaling factor.
+     * @returns {Promise<void>}
+     */
     setContentScale(scale) {
         return this._invokeSafe('setContentScale', {id: this._id, scale});
     }
 
+    /**
+     * 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() {
         throw new Error('Not supported on PopupProxy');
     }
 
+    /**
+     * Updates the outer theme of the popup.
+     * @returns {Promise<void>}
+     */
     updateTheme() {
         return this._invokeSafe('updateTheme', {id: this._id});
     }
 
+    /**
+     * Sets the custom styles for the outer popup container.
+     * @param {string} css The CSS rules.
+     * @param {boolean} useWebExtensionApi Whether or not web extension APIs should be used to inject the rules.
+     *   When web extension APIs are used, a DOM node is not generated, making it harder to detect the changes.
+     * @returns {Promise<void>}
+     */
     setCustomOuterCss(css, useWebExtensionApi) {
         return this._invokeSafe('setCustomOuterCss', {id: this._id, css, useWebExtensionApi});
     }
 
+    /**
+     * Gets the rectangle of the DOM frame, synchronously.
+     * @returns {{x: number, y: number, width: number, height: number, valid: boolean}} The rect.
+     *   `valid` is `false` for `PopupProxy`, since the DOM node is hosted in a different frame.
+     */
     getFrameRect() {
         return {x: 0, y: 0, width: 0, height: 0, valid: false};
     }
 
+    /**
+     * Gets the size of the DOM frame.
+     * @returns {Promise<{width: number, height: number, valid: boolean}>} The size and whether or not it is valid.
+     */
     getFrameSize() {
         return this._invokeSafe('popup.getFrameSize', {id: this._id}, {width: 0, height: 0, valid: false});
     }
 
+    /**
+     * Sets the size of the DOM frame.
+     * @param {number} width The desired width of the popup.
+     * @param {number} height The desired height of the popup.
+     * @returns {Promise<boolean>} `true` if the size assignment was successful, `false` otherwise.
+     */
     setFrameSize(width, height) {
         return this._invokeSafe('popup.setFrameSize', {id: this._id, width, height});
     }
diff --git a/ext/js/app/popup-window.js b/ext/js/app/popup-window.js
index 6f86c61e..61c627b8 100644
--- a/ext/js/app/popup-window.js
+++ b/ext/js/app/popup-window.js
@@ -15,7 +15,17 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+/**
+ * This class represents a popup that is hosted in a new native window.
+ */
 class PopupWindow extends EventDispatcher {
+    /**
+     * Creates a new instance.
+     * @param {object} details
+     * @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.
+     */
     constructor({
         id,
         depth,
@@ -30,6 +40,10 @@ class PopupWindow extends EventDispatcher {
 
     // Public properties
 
+    /**
+     * The ID of the popup.
+     * @type {string}
+     */
     get id() {
         return this._id;
     }
@@ -38,30 +52,63 @@ class PopupWindow extends EventDispatcher {
         return null;
     }
 
+    /**
+     * 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}
+     */
     set parent(value) {
         throw new Error('Not supported on PopupProxy');
     }
 
+    /**
+     * The popup child popup, which is always null for `PopupWindow` instances,
+     * since any potential child popups are in a different frame.
+     * @type {Popup}
+     */
     get child() {
         return null;
     }
 
+    /**
+     * Attempts to set the child popup.
+     * @param {Popup} value
+     * @throws Throws an error, since this class doesn't support children.
+     */
     set child(value) {
         throw new Error('Not supported on PopupProxy');
     }
 
+    /**
+     * The depth of the popup.
+     * @type {numer}
+     */
     get depth() {
         return this._depth;
     }
 
+    /**
+     * Gets the content window of the frame. This value is null,
+     * since the window is hosted in a different frame.
+     * @type {Window}
+     */
     get frameContentWindow() {
         return null;
     }
 
+    /**
+     * Gets the DOM node that contains the frame.
+     * @type {Element}
+     */
     get container() {
         return null;
     }
 
+    /**
+     * Gets the ID of the frame.
+     * @type {number}
+     */
     get frameId() {
         return this._frameId;
     }
@@ -69,67 +116,145 @@ class PopupWindow extends EventDispatcher {
 
     // Public functions
 
+    /**
+     * Sets the options context for the popup.
+     * @param {object} optionsContext The options context object.
+     * @returns {Promise<void>}
+     */
     setOptionsContext(optionsContext, source) {
         return this._invoke(false, 'setOptionsContext', {id: this._id, optionsContext, source});
     }
 
+    /**
+     * Hides the popup. This does nothing for `PopupWindow`.
+     * @param {boolean} _changeFocus Whether or not the parent popup or host frame should be focused.
+     */
     hide(_changeFocus) {
         // NOP
     }
 
+    /**
+     * Returns whether or not the popup is currently visible.
+     * @returns {Promise<boolean>} `true` if the popup is visible, `false` otherwise.
+     */
     async isVisible() {
         return (this._popupTabId !== null && await yomichan.api.isTabSearchPopup(this._popupTabId));
     }
 
+    /**
+     * Force assigns the visibility of the popup.
+     * @param {boolean} _value Whether or not the popup should be visible.
+     * @param {number} _priority The priority of the override.
+     * @returns {Promise<string?>} A token used which can be passed to `clearVisibleOverride`,
+     *   or null if the override wasn't assigned.
+     */
     async setVisibleOverride(_value, _priority) {
         return null;
     }
 
+    /**
+     * Clears a visibility override that was generated by `setVisibleOverride`.
+     * @param {string} _token The token returned from `setVisibleOverride`.
+     * @returns {boolean} `true` if the override existed and was removed, `false` otherwise.
+     */
     clearVisibleOverride(_token) {
         return false;
     }
 
+    /**
+     * Checks whether a point is contained within the popup's rect.
+     * @param {number} _x The x coordinate.
+     * @param {number} _y The y coordinate.
+     * @returns {Promise<boolean>} `true` if the point is contained within the popup's rect, `false` otherwise.
+     */
     async containsPoint(_x, _y) {
         return false;
     }
 
+    /**
+     * Shows and updates the positioning and content of the popup.
+     * @param {{optionsContext: object, elementRect: {x: number, y: number, width: number, height: number}, writingMode: string}} details Settings for the outer popup.
+     * @param {object} displayDetails The details parameter passed to `Display.setContent`; see that function for details.
+     * @returns {Promise<void>}
+     */
     async showContent(_details, displayDetails) {
         if (displayDetails === null) { return; }
         await this._invoke(true, 'setContent', {id: this._id, details: displayDetails});
     }
 
+    /**
+     * Sets the custom styles for the popup content.
+     * @param {string} css The CSS rules.
+     */
     setCustomCss(css) {
         return this._invoke(false, 'setCustomCss', {id: this._id, css});
     }
 
+    /**
+     * Stops the audio auto-play timer, if one has started.
+     */
     clearAutoPlayTimer() {
         return this._invoke(false, 'clearAutoPlayTimer', {id: this._id});
     }
 
+    /**
+     * Sets the scaling factor of the popup content.
+     * @param {number} scale The scaling factor.
+     */
     setContentScale(_scale) {
         // NOP
     }
 
+    /**
+     * 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() {
         throw new Error('Not supported on PopupWindow');
     }
 
+    /**
+     * Updates the outer theme of the popup.
+     */
     updateTheme() {
         // NOP
     }
 
+    /**
+     * Sets the custom styles for the outer popup container.
+     * This does nothing for `PopupWindow`.
+     * @param {string} _css The CSS rules.
+     * @param {boolean} _useWebExtensionApi Whether or not web extension APIs should be used to inject the rules.
+     *   When web extension APIs are used, a DOM node is not generated, making it harder to detect the changes.
+     */
     async setCustomOuterCss(_css, _useWebExtensionApi) {
         // NOP
     }
 
+    /**
+     * Gets the rectangle of the DOM frame, synchronously.
+     * @returns {{x: number, y: number, width: number, height: number, valid: boolean}} The rect.
+     *   `valid` is `false` for `PopupProxy`, since the DOM node is hosted in a different frame.
+     */
     getFrameRect() {
         return {x: 0, y: 0, width: 0, height: 0, valid: false};
     }
 
+    /**
+     * Gets the size of the DOM frame.
+     * @returns {Promise<{width: number, height: number, valid: boolean}>} The size and whether or not it is valid.
+     */
     async getFrameSize() {
         return {width: 0, height: 0, valid: false};
     }
 
+    /**
+     * Sets the size of the DOM frame.
+     * @param {number} _width The desired width of the popup.
+     * @param {number} _height The desired height of the popup.
+     * @returns {Promise<boolean>} `true` if the size assignment was successful, `false` otherwise.
+     */
     async setFrameSize(_width, _height) {
         return false;
     }
diff --git a/ext/js/app/popup.js b/ext/js/app/popup.js
index 3a29563d..7581c8d7 100644
--- a/ext/js/app/popup.js
+++ b/ext/js/app/popup.js
@@ -21,7 +21,18 @@
  * dynamicLoader
  */
 
+/**
+ * This class is the container which hosts the display of search results.
+ */
 class Popup extends EventDispatcher {
+    /**
+     * Creates a new instance.
+     * @param {object} details
+     * @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.
+     * @param {boolean} details.childrenSupported Whether or not the popup is able to show child popups.
+     */
     constructor({
         id,
         depth,
@@ -59,44 +70,84 @@ class Popup extends EventDispatcher {
 
     // Public properties
 
+    /**
+     * The ID of the popup.
+     * @type {string}
+     */
     get id() {
         return this._id;
     }
 
+    /**
+     * The parent of the popup.
+     * @type {Popup}
+     */
     get parent() {
         return this._parent;
     }
 
+    /**
+     * Sets the parent popup.
+     * @param {Popup} value The parent popup to assign.
+     */
     set parent(value) {
         this._parent = value;
     }
 
+    /**
+     * The child of the popup.
+     * @type {Popup}
+     */
     get child() {
         return this._child;
     }
 
+    /**
+     * Sets the child popup.
+     * @param {Popup} value The child popup to assign.
+     */
     set child(value) {
         this._child = value;
     }
 
+    /**
+     * The depth of the popup.
+     * @type {numer}
+     */
     get depth() {
         return this._depth;
     }
 
+    /**
+     * Gets the content window of the frame, which can be `null`
+     * depending on the current state of the frame.
+     * @type {?Window}
+     */
     get frameContentWindow() {
         return this._frame.contentWindow;
     }
 
+    /**
+     * Gets the DOM node that contains the frame.
+     * @type {Element}
+     */
     get container() {
         return this._container;
     }
 
+    /**
+     * Gets the ID of the frame.
+     * @type {number}
+     */
     get frameId() {
         return this._frameId;
     }
 
     // Public functions
 
+    /**
+     * Prepares the popup for use.
+     */
     prepare() {
         this._frame.addEventListener('mouseover', this._onFrameMouseOver.bind(this));
         this._frame.addEventListener('mouseout', this._onFrameMouseOut.bind(this));
@@ -108,11 +159,19 @@ class Popup extends EventDispatcher {
         this._onVisibleChange({value: this.isVisibleSync()});
     }
 
+    /**
+     * Sets the options context for the popup.
+     * @param {object} optionsContext The options context object.
+     */
     async setOptionsContext(optionsContext) {
         await this._setOptionsContext(optionsContext);
         await this._invokeSafe('setOptionsContext', {optionsContext});
     }
 
+    /**
+     * Hides the popup.
+     * @param {boolean} changeFocus Whether or not the parent popup or host frame should be focused.
+     */
     hide(changeFocus) {
         if (!this.isVisibleSync()) {
             return;
@@ -127,18 +186,40 @@ class Popup extends EventDispatcher {
         }
     }
 
+    /**
+     * Returns whether or not the popup is currently visible.
+     * @returns {Promise<boolean>} `true` if the popup is visible, `false` otherwise.
+     */
     async isVisible() {
         return this.isVisibleSync();
     }
 
+    /**
+     * Force assigns the visibility of the popup.
+     * @param {boolean} value Whether or not the popup should be visible.
+     * @param {number} priority The priority of the override.
+     * @returns {Promise<string?>} A token used which can be passed to `clearVisibleOverride`,
+     *   or null if the override wasn't assigned.
+     */
     async setVisibleOverride(value, priority) {
         return this._visible.setOverride(value, priority);
     }
 
+    /**
+     * Clears a visibility override that was generated by `setVisibleOverride`.
+     * @param {string} token The token returned from `setVisibleOverride`.
+     * @returns {Promise<boolean>} `true` if the override existed and was removed, `false` otherwise.
+     */
     async clearVisibleOverride(token) {
         return this._visible.clearOverride(token);
     }
 
+    /**
+     * Checks whether a point is contained within the popup's rect.
+     * @param {number} x The x coordinate.
+     * @param {number} y The y coordinate.
+     * @returns {Promise<boolean>} `true` if the point is contained within the popup's rect, `false` otherwise.
+     */
     async containsPoint(x, y) {
         for (let popup = this; popup !== null && popup.isVisibleSync(); popup = popup.child) {
             const rect = popup.getFrameRect();
@@ -149,6 +230,12 @@ class Popup extends EventDispatcher {
         return false;
     }
 
+    /**
+     * Shows and updates the positioning and content of the popup.
+     * @param {{optionsContext: object, elementRect: {x: number, y: number, width: number, height: number}, writingMode: string}} details Settings for the outer popup.
+     * @param {object} displayDetails The details parameter passed to `Display.setContent`; see that function for details.
+     * @returns {Promise<void>}
+     */
     async showContent(details, displayDetails) {
         if (this._options === null) { throw new Error('Options not assigned'); }
 
@@ -166,24 +253,43 @@ class Popup extends EventDispatcher {
         }
     }
 
+    /**
+     * Sets the custom styles for the popup content.
+     * @param {string} css The CSS rules.
+     */
     setCustomCss(css) {
         this._invokeSafe('setCustomCss', {css});
     }
 
+    /**
+     * Stops the audio auto-play timer, if one has started.
+     */
     clearAutoPlayTimer() {
         this._invokeSafe('clearAutoPlayTimer');
     }
 
+    /**
+     * Sets the scaling factor of the popup content.
+     * @param {number} scale The scaling factor.
+     */
     setContentScale(scale) {
         this._contentScale = scale;
         this._frame.style.fontSize = `${scale}px`;
         this._invokeSafe('setContentScale', {scale});
     }
 
+    /**
+     * Returns whether or not the popup is currently visible, synchronously.
+     * @returns {boolean} `true` if the popup is visible, `false` otherwise.
+     */
     isVisibleSync() {
         return this._visible.value;
     }
 
+    /**
+     * Updates the outer theme of the popup.
+     * @returns {Promise<void>}
+     */
     updateTheme() {
         const {popupTheme, popupOuterTheme} = this._options.general;
         this._frame.dataset.theme = popupTheme;
@@ -191,6 +297,12 @@ class Popup extends EventDispatcher {
         this._frame.dataset.siteColor = this._getSiteColor();
     }
 
+    /**
+     * Sets the custom styles for the outer popup container.
+     * @param {string} css The CSS rules.
+     * @param {boolean} useWebExtensionApi Whether or not web extension APIs should be used to inject the rules.
+     *   When web extension APIs are used, a DOM node is not generated, making it harder to detect the changes.
+     */
     async setCustomOuterCss(css, useWebExtensionApi) {
         let parentNode = null;
         const inShadow = (this._shadow !== null);
@@ -202,16 +314,31 @@ class Popup extends EventDispatcher {
         this.trigger('customOuterCssChanged', {node, useWebExtensionApi, inShadow});
     }
 
+    /**
+     * Gets the rectangle of the DOM frame, synchronously.
+     * @returns {{x: number, y: number, width: number, height: number, valid: boolean}} The rect.
+     *   `valid` is `false` for `PopupProxy`, since the DOM node is hosted in a different frame.
+     */
     getFrameRect() {
         const {left, top, width, height} = this._frame.getBoundingClientRect();
         return {x: left, y: top, width, height, valid: true};
     }
 
+    /**
+     * Gets the size of the DOM frame.
+     * @returns {Promise<{width: number, height: number, valid: boolean}>} The size and whether or not it is valid.
+     */
     async getFrameSize() {
         const {width, height} = this._frame.getBoundingClientRect();
         return {width, height, valid: true};
     }
 
+    /**
+     * Sets the size of the DOM frame.
+     * @param {number} width The desired width of the popup.
+     * @param {number} height The desired height of the popup.
+     * @returns {Promise<boolean>} `true` if the size assignment was successful, `false` otherwise.
+     */
     async setFrameSize(width, height) {
         this._setFrameSize(width, height);
         return true;
diff --git a/ext/js/core.js b/ext/js/core.js
index c43d7828..09468be7 100644
--- a/ext/js/core.js
+++ b/ext/js/core.js
@@ -17,8 +17,8 @@
 
 /**
  * Converts an `Error` object to a serializable JSON object.
- * @param error An error object to convert.
- * @returns A simple object which can be serialized by `JSON.stringify()`.
+ * @param {*} error An error object to convert.
+ * @returns {{name: string, message: string, stack: string, data?: *}|{value: *, hasValue: boolean}} A simple object which can be serialized by `JSON.stringify()`.
  */
 function serializeError(error) {
     try {
@@ -44,8 +44,8 @@ function serializeError(error) {
 
 /**
  * Converts a serialized erorr into a standard `Error` object.
- * @param serializedError A simple object which was initially generated by serializeError.
- * @returns A new `Error` instance.
+ * @param {{name: string, message: string, stack: string, data?: *}|{value: *, hasValue: boolean}} serializedError A simple object which was initially generated by serializeError.
+ * @returns {Error|*} A new `Error` instance.
  */
 function deserializeError(serializedError) {
     if (serializedError.hasValue) {
@@ -62,8 +62,8 @@ function deserializeError(serializedError) {
 
 /**
  * Checks whether a given value is a non-array object.
- * @param value The value to check.
- * @returns `true` if the value is an object and not an array, `false` otherwise.
+ * @param {*} value The value to check.
+ * @returns {boolean} `true` if the value is an object and not an array, `false` otherwise.
  */
 function isObject(value) {
     return typeof value === 'object' && value !== null && !Array.isArray(value);
@@ -72,8 +72,8 @@ function isObject(value) {
 /**
  * Converts any string into a form that can be passed into the RegExp constructor.
  * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
- * @param string The string to convert to a valid regular expression.
- * @returns The escaped string.
+ * @param {string} string The string to convert to a valid regular expression.
+ * @returns {string} The escaped string.
  */
 function escapeRegExp(string) {
     return string.replace(/[.*+\-?^${}()|[\]\\]/g, '\\$&');
@@ -81,8 +81,8 @@ function escapeRegExp(string) {
 
 /**
  * Reverses a string.
- * @param string The string to reverse.
- * @returns The returned string, which retains proper UTF-16 surrogate pair order.
+ * @param {string} string The string to reverse.
+ * @returns {string} The returned string, which retains proper UTF-16 surrogate pair order.
  */
 function stringReverse(string) {
     return [...string].reverse().join('');
@@ -90,8 +90,8 @@ function stringReverse(string) {
 
 /**
  * Creates a deep clone of an object or value. This is similar to `JSON.parse(JSON.stringify(value))`.
- * @param value The value to clone.
- * @returns A new clone of the value.
+ * @param {*} value The value to clone.
+ * @returns {*} A new clone of the value.
  * @throws An error if the value is circular and cannot be cloned.
  */
 const clone = (() => {
@@ -163,9 +163,9 @@ const clone = (() => {
 
 /**
  * Checks if an object or value is deeply equal to another object or value.
- * @param value1 The first value to check.
- * @param value2 The second value to check.
- * @returns `true` if the values are the same object, or deeply equal without cycles. `false` otherwise.
+ * @param {*} value1 The first value to check.
+ * @param {*} value2 The second value to check.
+ * @returns {boolean} `true` if the values are the same object, or deeply equal without cycles. `false` otherwise.
  */
 const deepEqual = (() => {
     // eslint-disable-next-line no-shadow
@@ -235,8 +235,8 @@ const deepEqual = (() => {
 
 /**
  * Creates a new base-16 (lower case) string of a sequence of random bytes of the given length.
- * @param length The number of bytes the string represents. The returned string's length will be twice as long.
- * @returns A string of random characters.
+ * @param {number} length The number of bytes the string represents. The returned string's length will be twice as long.
+ * @returns {string} A string of random characters.
  */
 function generateId(length) {
     const array = new Uint8Array(length);
@@ -250,7 +250,7 @@ function generateId(length) {
 
 /**
  * Creates an unresolved promise that can be resolved later, outside the promise's executor function.
- * @returns 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;
@@ -264,9 +264,9 @@ function deferPromise() {
 
 /**
  * Creates a promise that is resolved after a set delay.
- * @param delay How many milliseconds until the promise should be resolved. If 0, the promise is immediately resolved.
- * @param resolveValue Optional; the value returned when the promise is resolved.
- * @returns A promise with two additional properties: `resolve` and `reject`, which can be used to complete the promise early.
+ * @param {number} delay How many milliseconds until the promise should be resolved. If 0, the promise is immediately resolved.
+ * @param {*} [resolveValue] The value returned when the promise is resolved.
+ * @returns {Promise} A promise with two additional properties: `resolve` and `reject`, which can be used to complete the promise early.
  */
 function promiseTimeout(delay, resolveValue) {
     if (delay <= 0) {
@@ -306,8 +306,8 @@ function promiseTimeout(delay, resolveValue) {
 
 /**
  * Creates a promise that will resolve after the next animation frame, using `requestAnimationFrame`.
- * @param timeout Optional; a maximum duration (in milliseconds) to wait until the promise resolves. If null or omitted, no timeout is used.
- * @returns A promise that is resolved with `{time, timeout}`, where `time` is the timestamp from `requestAnimationFrame`,
+ * @param {number} [timeout] A maximum duration (in milliseconds) to wait until the promise resolves. If null or omitted, no timeout is used.
+ * @returns {Promise<{time: number, timeout: number}>} A promise that is resolved with `{time, timeout}`, where `time` is the timestamp from `requestAnimationFrame`,
  *  and `timeout` is a boolean indicating whether the cause was a timeout or not.
  * @throws The promise throws an error if animation is not supported in this context, such as in a service worker.
  */
@@ -349,16 +349,17 @@ function promiseAnimationFrame(timeout=null) {
 /**
  * Invokes a standard message handler. This function is used to react and respond
  * to communication messages within the extension.
- * @param handler A handler function which is passed `params` and `...extraArgs` as arguments.
- * @param async Whether or not the handler is async or not. Values include `false`, `true`, or `'dynamic'`.
+ * @param {object} details
+ * @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 params Information which was passed with the original message.
- * @param callback A callback function which is invoked after the handler has completed. The value passed
+ * @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
  *   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.
- * @param extraArgs Additional arguments which are passed to the `handler` function.
- * @returns `true` if the function is invoked asynchronously, `false` otherwise.
+ * @param {...*} extraArgs Additional arguments which are passed to the `handler` function.
+ * @returns {boolean} `true` if the function is invoked asynchronously, `false` otherwise.
  */
 function invokeMessageHandler({handler, async}, params, callback, ...extraArgs) {
     try {
@@ -395,9 +396,9 @@ class EventDispatcher {
 
     /**
      * Triggers an event with the given name and specified argument.
-     * @param eventName The string representing the event's name.
-     * @param details Optional; the argument passed to the callback functions.
-     * @returns `true` if any callbacks were registered, `false` otherwise.
+     * @param {string} eventName The string representing the event's name.
+     * @param {*} [details] The argument passed to the callback functions.
+     * @returns {boolean} `true` if any callbacks were registered, `false` otherwise.
      */
     trigger(eventName, details) {
         const callbacks = this._eventMap.get(eventName);
@@ -411,8 +412,8 @@ class 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.
      */
     on(eventName, callback) {
         let callbacks = this._eventMap.get(eventName);
@@ -425,9 +426,9 @@ class 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 callbacks = this._eventMap.get(eventName);
@@ -448,8 +449,8 @@ class EventDispatcher {
 
     /**
      * Checks if an event has any listeners.
-     * @param eventName The string representing the event's name.
-     * @returns `true` if the event has listeners, `false` otherwise.
+     * @param {string} eventName The string representing the event's name.
+     * @returns {boolean} `true` if the event has listeners, `false` otherwise.
      */
     hasListeners(eventName) {
         const callbacks = this._eventMap.get(eventName);
@@ -470,7 +471,7 @@ class EventListenerCollection {
 
     /**
      * Returns the number of event listeners that are currently in the object.
-     * @returns The number of event listeners that are currently in the object.
+     * @type {number}
      */
     get size() {
         return this._eventListeners.length;
@@ -478,9 +479,9 @@ class EventListenerCollection {
 
     /**
      * Adds an event listener of a generic type.
-     * @param type The type of event listener, which can be 'addEventListener', 'addListener', or 'on'.
-     * @param object The object to add the event listener to.
-     * @param args The argument array passed to the object's event listener adding function.
+     * @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.
      * @throws An error if type is not an expected value.
      */
     addGeneric(type, object, ...args) {
@@ -494,8 +495,8 @@ class EventListenerCollection {
 
     /**
      * Adds an event listener using `object.addEventListener`. The listener will later be removed using `object.removeEventListener`.
-     * @param object The object to add the event listener to.
-     * @param args The argument array passed to the `addEventListener`/`removeEventListener` functions.
+     * @param {object} object The object to add the event listener to.
+     * @param {...*} args The argument array passed to the `addEventListener`/`removeEventListener` functions.
      */
     addEventListener(object, ...args) {
         object.addEventListener(...args);
@@ -504,8 +505,8 @@ class EventListenerCollection {
 
     /**
      * Adds an event listener using `object.addListener`. The listener will later be removed using `object.removeListener`.
-     * @param object The object to add the event listener to.
-     * @param args The argument array passed to the `addListener`/`removeListener` function.
+     * @param {object} object The object to add the event listener to.
+     * @param {...*} args The argument array passed to the `addListener`/`removeListener` function.
      */
     addListener(object, ...args) {
         object.addListener(...args);
@@ -514,8 +515,8 @@ class EventListenerCollection {
 
     /**
      * Adds an event listener using `object.on`. The listener will later be removed using `object.off`.
-     * @param object The object to add the event listener to.
-     * @param args The argument array passed to the `on`/`off` function.
+     * @param {object} object The object to add the event listener to.
+     * @param {...*} args The argument array passed to the `on`/`off` function.
      */
     on(object, ...args) {
         object.on(...args);
@@ -553,7 +554,7 @@ class EventListenerCollection {
 class DynamicProperty extends EventDispatcher {
     /**
      * Creates a new instance with the specified value.
-     * @param value The value to assign.
+     * @param {*} value The value to assign.
      */
     constructor(value) {
         super();
@@ -565,6 +566,7 @@ class DynamicProperty extends EventDispatcher {
     /**
      * Gets the default value for the property, which is assigned to the
      * public value property when no overrides are present.
+     * @type {*}
      */
     get defaultValue() {
         return this._defaultValue;
@@ -574,7 +576,7 @@ class DynamicProperty extends EventDispatcher {
      * Assigns the default value for the property. If no overrides are present
      * and if the value is different than the current default value,
      * the 'change' event will be triggered.
-     * @param value The value to assign.
+     * @param {*} value The value to assign.
      */
     set defaultValue(value) {
         this._defaultValue = value;
@@ -583,6 +585,7 @@ class DynamicProperty extends EventDispatcher {
 
     /**
      * Gets the current value for the property, taking any overrides into account.
+     * @type {*}
      */
     get value() {
         return this._value;
@@ -590,6 +593,7 @@ class DynamicProperty extends EventDispatcher {
 
     /**
      * Gets the number of overrides added to the property.
+     * @type {*}
      */
     get overrideCount() {
         return this._overrides.length;
@@ -602,9 +606,9 @@ class DynamicProperty extends EventDispatcher {
      * If the newly added override has the highest priority of all overrides
      * and if the override value is different from the current value,
      * the 'change' event will be fired.
-     * @param value The override value to assign.
-     * @param priority The priority value to use, as a number.
-     * @returns A string token which can be passed to the clearOverride function
+     * @param {*} value The override value to assign.
+     * @param {number} [priority] The priority value to use, as a number.
+     * @returns {string} A string token which can be passed to the clearOverride function
      *  to remove the override.
      */
     setOverride(value, priority=0) {
@@ -623,8 +627,8 @@ class DynamicProperty extends EventDispatcher {
      * Removes a specific override value. If the removed override
      * had the highest priority, and the new value is different from
      * the previous value, the 'change' event will be fired.
-     * @param token The token for the corresponding override which is to be removed.
-     * @returns true if an override was returned, false otherwise.
+     * @param {string} token The token for the corresponding override which is to be removed.
+     * @returns {boolean} `true` if an override was returned, `false` otherwise.
      */
     clearOverride(token) {
         for (let i = 0, ii = this._overrides.length; i < ii; ++i) {
@@ -670,10 +674,10 @@ class Logger extends EventDispatcher {
 
     /**
      * Logs a generic error. This will trigger the 'log' event with the same arguments as the function invocation.
-     * @param error The error to log. This is typically an `Error` or `Error`-like object.
-     * @param level The level to log at. Values include `'info'`, `'debug'`, `'warn'`, and `'error'`.
+     * @param {Error|object|*} error The error to log. This is typically an `Error` or `Error`-like object.
+     * @param {string} level The level to log at. Values include `'info'`, `'debug'`, `'warn'`, and `'error'`.
      *   Other values will be logged at a non-error level.
-     * @param context An optional context object for the error which should typically include a `url` field.
+     * @param {?object} [context] An optional context object for the error which should typically include a `url` field.
      */
     log(error, level, context=null) {
         if (!isObject(context)) {
@@ -735,8 +739,8 @@ class Logger extends EventDispatcher {
 
     /**
      * Logs a warning. This function invokes `log` internally.
-     * @param error The error to log. This is typically an `Error` or `Error`-like object.
-     * @param context An optional context object for the error which should typically include a `url` field.
+     * @param {Error|object|*} error The error to log. This is typically an `Error` or `Error`-like object.
+     * @param {?object} context An optional context object for the error which should typically include a `url` field.
      */
     warn(error, context=null) {
         this.log(error, 'warn', context);
@@ -744,8 +748,8 @@ class Logger extends EventDispatcher {
 
     /**
      * Logs an error. This function invokes `log` internally.
-     * @param error The error to log. This is typically an `Error` or `Error`-like object.
-     * @param context An optional context object for the error which should typically include a `url` field.
+     * @param {Error|object|*} error The error to log. This is typically an `Error` or `Error`-like object.
+     * @param {?object} context An optional context object for the error which should typically include a `url` field.
      */
     error(error, context=null) {
         this.log(error, 'error', context);
diff --git a/ext/js/yomichan.js b/ext/js/yomichan.js
index 1eae2d4d..c65e2f7d 100644
--- a/ext/js/yomichan.js
+++ b/ext/js/yomichan.js
@@ -39,7 +39,13 @@ if ((() => {
     chrome = browser;
 }
 
+/**
+ * The Yomichan class is a core component through which various APIs are handled and invoked.
+ */
 class Yomichan extends EventDispatcher {
+    /**
+     * Creates a new instance. The instance should not be used until it has been fully prepare()'d.
+     */
     constructor() {
         super();
 
@@ -72,24 +78,44 @@ class Yomichan extends EventDispatcher {
         ]);
     }
 
-    // Public
-
+    /**
+     * Whether the current frame is the background page/service worker or not.
+     * @type {boolean}
+     */
     get isBackground() {
         return this._isBackground;
     }
 
+    /**
+     * Whether or not the extension is unloaded.
+     * @type {boolean}
+     */
     get isExtensionUnloaded() {
         return this._isExtensionUnloaded;
     }
 
+    /**
+     * Gets the API instance for communicating with the backend.
+     * This value will be null on the background page/service worker.
+     * @type {API}
+     */
     get api() {
         return this._api;
     }
 
+    /**
+     * Gets the CrossFrameAPI instance for communicating with different frames.
+     * This value will be null on the background page/service worker.
+     * @type {CrossFrameAPI}
+     */
     get crossFrame() {
         return this._crossFrame;
     }
 
+    /**
+     * Prepares the instance for use.
+     * @param {boolean} [isBackground=false] Assigns whether this instance is being used from the background page/service worker.
+     */
     async prepare(isBackground=false) {
         this._isBackground = isBackground;
         chrome.runtime.onMessage.addListener(this._onMessage.bind(this));
@@ -107,11 +133,20 @@ class Yomichan extends EventDispatcher {
         }
     }
 
+    /**
+     * Sends a message to the backend indicating that the frame is ready and all script
+     * setup has completed.
+     */
     ready() {
         this._isReady = true;
         this.sendMessage({action: 'yomichanReady'});
     }
 
+    /**
+     * 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.
+     */
     isExtensionUrl(url) {
         try {
             return url.startsWith(chrome.runtime.getURL('/'));
@@ -120,6 +155,11 @@ class Yomichan extends EventDispatcher {
         }
     }
 
+    /**
+     * 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.
+     */
     sendMessage(...args) {
         try {
             return chrome.runtime.sendMessage(...args);
@@ -129,6 +169,11 @@ class Yomichan extends EventDispatcher {
         }
     }
 
+    /**
+     * 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.
+     */
     connect(...args) {
         try {
             return chrome.runtime.connect(...args);
@@ -138,6 +183,9 @@ class Yomichan extends EventDispatcher {
         }
     }
 
+    /**
+     * Runs chrome.runtime.connect() with additional exception handling events.
+     */
     triggerExtensionUnloaded() {
         this._isExtensionUnloaded = true;
         if (this._isTriggeringExtensionUnloaded) { return; }
@@ -200,4 +248,7 @@ class Yomichan extends EventDispatcher {
     }
 }
 
+/**
+ * The default Yomichan class instance.
+ */
 const yomichan = new Yomichan();