1 files changed, 110 insertions, 0 deletions
diff --git a/ext/js/dom/text-source-range.js b/ext/js/dom/text-source-range.js
index e03783a5..a0225748 100644
--- a/ext/js/dom/text-source-range.js
+++ b/ext/js/dom/text-source-range.js
@@ -20,7 +20,29 @@
  * DocumentUtil
  */
 
+/**
+ * This class represents a text source that comes from text nodes in the document.
+ * Sometimes a temporary "imposter" element is created and used to store the text.
+ * This element is typically hidden from the page and removed after scanning has completed.
+ */
 class TextSourceRange {
+    /**
+     * Creates a new instance of the class.
+     * @param {Range} range The selection range.
+     * @param {number} rangeStartOffset The `startOffset` of the range. This is somewhat redundant
+     *   with the `range` parameter, but it is used when for when imposter elements are removed.
+     * @param {string} content The `toString()` value of the range. This is somewhat redundant
+     *   with the `range` parameter, but it is used when for when imposter elements are removed.
+     * @param {?Element} imposterElement The temporary imposter element.
+     * @param {?Element} imposterSourceElement The source element which the imposter is imitating.
+     *   Must not be `null` if imposterElement is specified.
+     * @param {?Rect[]} cachedRects A set of cached `DOMRect`s representing the rects of the text source,
+     *   which can be used after the imposter element is removed from the page.
+     *   Must not be `null` if imposterElement is specified.
+     * @param {?Rect} cachedSourceRect A cached `DOMRect` representing the rect of the `imposterSourceElement`,
+     *   which can be used after the imposter element is removed from the page.
+     *   Must not be `null` if imposterElement is specified.
+     */
     constructor(range, rangeStartOffset, content, imposterElement, imposterSourceElement, cachedRects, cachedSourceRect) {
         this._range = range;
         this._rangeStartOffset = rangeStartOffset;
@@ -31,22 +53,42 @@ class TextSourceRange {
         this._cachedSourceRect = cachedSourceRect;
     }
 
+    /**
+     * Gets the type name of this instance.
+     * @type {string}
+     */
     get type() {
         return 'range';
     }
 
+    /**
+     * The internal range object.
+     * @type {Range}
+     */
     get range() {
         return this._range;
     }
 
+    /**
+     * The starting offset for the range.
+     * @type {Range}
+     */
     get rangeStartOffset() {
         return this._rangeStartOffset;
     }
 
+    /**
+     * The source element that the imposter element is imitating, if present.
+     * @type {?Element}
+     */
     get imposterSourceElement() {
         return this._imposterSourceElement;
     }
 
+    /**
+     * Creates a clone of the instance.
+     * @returns {TextSourceRange} The new clone.
+     */
     clone() {
         return new TextSourceRange(
             this._range.cloneRange(),
@@ -59,16 +101,31 @@ class TextSourceRange {
         );
     }
 
+    /**
+     * Performs any cleanup that is necessary after the element has been used.
+     */
     cleanup() {
         if (this._imposterElement !== null && this._imposterElement.parentNode !== null) {
             this._imposterElement.parentNode.removeChild(this._imposterElement);
         }
     }
 
+    /**
+     * Gets the selected text of element, which is the `toString()` version of the range.
+     * @returns {string} The text content.
+     */
     text() {
         return this._content;
     }
 
+    /**
+     * Moves the end offset of the text by a set amount of unicode codepoints.
+     * @param {number} length The maximum number of codepoints to move by.
+     * @param {boolean} fromEnd Whether to move the offset from the current end position (if `true`) or the start position (if `false`).
+     * @param {boolean} layoutAwareScan Whether or not HTML layout information should be used to generate
+     *   the string content when scanning.
+     * @returns {number} The actual number of characters (not codepoints) that were read.
+     */
     setEndOffset(length, fromEnd, layoutAwareScan) {
         let node;
         let offset;
@@ -85,6 +142,13 @@ class TextSourceRange {
         return length - state.remainder;
     }
 
+    /**
+     * Moves the start offset of the text by a set amount of unicode codepoints.
+     * @param {number} length The maximum number of codepoints to move by.
+     * @param {boolean} layoutAwareScan Whether or not HTML layout information should be used to generate
+     *   the string content when scanning.
+     * @returns {number} The actual number of characters (not codepoints) that were read.
+     */
     setStartOffset(length, layoutAwareScan) {
         const state = new DOMTextScanner(this._range.startContainer, this._range.startOffset, !layoutAwareScan, layoutAwareScan).seek(-length);
         this._range.setStart(state.node, state.offset);
@@ -93,16 +157,28 @@ class TextSourceRange {
         return length - state.remainder;
     }
 
+    /**
+     * Gets the rects that represent the position and bounds of the text source.
+     * @returns {DOMRect[]} The rects.
+     */
     getRects() {
         if (this._isImposterDisconnected()) { return this._getCachedRects(); }
         return DocumentUtil.convertMultipleRectZoomCoordinates(this._range.getClientRects(), this._range.startContainer);
     }
 
+    /**
+     * Gets writing mode that is used for this element.
+     * See: https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode.
+     * @returns {string} The rects.
+     */
     getWritingMode() {
         const node = this._isImposterDisconnected() ? this._imposterSourceElement : this._range.startContainer;
         return DocumentUtil.getElementWritingMode(node !== null ? node.parentElement : null);
     }
 
+    /**
+     * Selects the text source in the document.
+     */
     select() {
         if (this._imposterElement !== null) { return; }
         const selection = window.getSelection();
@@ -110,12 +186,22 @@ class TextSourceRange {
         selection.addRange(this._range);
     }
 
+    /**
+     * Deselects the text source in the document.
+     */
     deselect() {
         if (this._imposterElement !== null) { return; }
         const selection = window.getSelection();
         selection.removeAllRanges();
     }
 
+    /**
+     * Checks whether another text source has the same starting point.
+     * @param {TextSourceElement|TextSourceRange} other The other source to test.
+     * @returns {boolean} `true` if the starting points are equivalent, `false` otherwise.
+     * @throws {Error} An exception can be thrown if `Range.compareBoundaryPoints` fails,
+     *   which shouldn't happen, but the handler is kept in case of unexpected errors.
+     */
     hasSameStart(other) {
         if (!(
             typeof other === 'object' &&
@@ -142,24 +228,48 @@ class TextSourceRange {
         }
     }
 
+    /**
+     * Gets a list of the nodes in this text source's range.
+     * @returns {Node[]} The nodes in the range.
+     */
     getNodesInRange() {
         return DocumentUtil.getNodesInRange(this._range);
     }
 
+    /**
+     * Creates a new instance for a given range.
+     * @param {Range} range The source range.
+     * @returns {TextSourceRange} A new instance of the class corresponding to the range.
+     */
     static create(range) {
         return new TextSourceRange(range, range.startOffset, range.toString(), null, null, null, null);
     }
 
+    /**
+     * Creates a new instance for a given range using an imposter element.
+     * @param {Range} range The source range.
+     * @param {Element} imposterElement The temporary imposter element.
+     * @param {Element} imposterSourceElement The source element which the imposter is imitating.
+     * @returns {TextSourceRange} A new instance of the class corresponding to the range.
+     */
     static createFromImposter(range, imposterElement, imposterSourceElement) {
         const cachedRects = DocumentUtil.convertMultipleRectZoomCoordinates(range.getClientRects(), range.startContainer);
         const cachedSourceRect = DocumentUtil.convertRectZoomCoordinates(imposterSourceElement.getBoundingClientRect(), imposterSourceElement);
         return new TextSourceRange(range, range.startOffset, range.toString(), imposterElement, imposterSourceElement, cachedRects, cachedSourceRect);
     }
 
+    /**
+     * Checks whether the imposter element has been removed, if the instance is using one.
+     * @returns {boolean} `true` if the instance has an imposter and it's no longer connected to the document, `false` otherwise.
+     */
     _isImposterDisconnected() {
         return this._imposterElement !== null && !this._imposterElement.isConnected;
     }
 
+    /**
+     * Gets the cached rects for a disconnected imposter element.
+     * @returns {Rect[]} The rects for the element.
+     */
     _getCachedRects() {
         const sourceRect = DocumentUtil.convertRectZoomCoordinates(this._imposterSourceElement.getBoundingClientRect(), this._imposterSourceElement);
         return DocumentUtil.offsetDOMRects(