1 files changed, 38 insertions, 8 deletions

diff --git a/ext/js/accessibility/google-docs-util.js b/ext/js/accessibility/google-docs-util.js
index e170f334..9db45cc1 100644
--- a/ext/js/accessibility/google-docs-util.js
+++ b/ext/js/accessibility/google-docs-util.js
@@ -29,8 +29,8 @@ export class GoogleDocsUtil {
      * Coordinates are provided in [client space](https://developer.mozilla.org/en-US/docs/Web/CSS/CSSOM_View/Coordinate_systems).
      * @param {number} x The x coordinate to search at.
      * @param {number} y The y coordinate to search at.
-     * @param {GetRangeFromPointOptions} options Options to configure how element detection is performed.
-     * @returns {?TextSourceRange|TextSourceElement} A range for the hovered text or element, or `null` if no applicable content was found.
+     * @param {import('document-util').GetRangeFromPointOptions} options Options to configure how element detection is performed.
+     * @returns {?TextSourceRange} A range for the hovered text or element, or `null` if no applicable content was found.
      */
     static getRangeFromPoint(x, y, {normalizeCssZoom}) {
         const styleNode = this._getStyleNode();
@@ -46,10 +46,13 @@ export class GoogleDocsUtil {
         return null;
     }
 
+    /**
+     * @returns {HTMLStyleElement}
+     */
     static _getStyleNode() {
         // This <style> node is necessary to force the SVG <rect> elements to have a fill,
         // which allows them to be included in document.elementsFromPoint's return value.
-        if (this._styleNode === null) {
+        if (typeof this._styleNode === 'undefined') {
             const style = document.createElement('style');
             style.textContent = [
                 '.kix-canvas-tile-content{pointer-events:none!important;}',
@@ -64,21 +67,34 @@ export class GoogleDocsUtil {
         return this._styleNode;
     }
 
+    /**
+     * @param {Element} element
+     * @param {string} text
+     * @param {number} x
+     * @param {number} y
+     * @param {boolean} normalizeCssZoom
+     * @returns {TextSourceRange}
+     */
     static _createRange(element, text, x, y, normalizeCssZoom) {
         // Create imposter
         const content = document.createTextNode(text);
         const svgText = document.createElementNS('http://www.w3.org/2000/svg', 'text');
         const transform = element.getAttribute('transform') || '';
         const font = element.getAttribute('data-font-css') || '';
-        svgText.setAttribute('x', element.getAttribute('x'));
-        svgText.setAttribute('y', element.getAttribute('y'));
+        const elementX = element.getAttribute('x');
+        const elementY = element.getAttribute('y');
+        if (typeof elementX === 'string') { svgText.setAttribute('x', elementX); }
+        if (typeof elementY === 'string') { svgText.setAttribute('y', elementY); }
         svgText.appendChild(content);
         const textStyle = svgText.style;
         this._setImportantStyle(textStyle, 'all', 'initial');
         this._setImportantStyle(textStyle, 'transform', transform);
         this._setImportantStyle(textStyle, 'font', font);
         this._setImportantStyle(textStyle, 'text-anchor', 'start');
-        element.parentNode.appendChild(svgText);
+        const {parentNode} = element;
+        if (parentNode !== null) {
+            parentNode.appendChild(svgText);
+        }
 
         // Adjust offset
         const elementRect = element.getBoundingClientRect();
@@ -93,6 +109,13 @@ export class GoogleDocsUtil {
         return TextSourceRange.createFromImposter(range, svgText, element);
     }
 
+    /**
+     * @param {Text} textNode
+     * @param {number} x
+     * @param {number} y
+     * @param {boolean} normalizeCssZoom
+     * @returns {Range}
+     */
     static _getRangeWithPoint(textNode, x, y, normalizeCssZoom) {
         if (normalizeCssZoom) {
             const scale = DocumentUtil.computeZoomScale(textNode);
@@ -101,7 +124,7 @@ export class GoogleDocsUtil {
         }
         const range = document.createRange();
         let start = 0;
-        let end = textNode.nodeValue.length;
+        let end = /** @type {string} */ (textNode.nodeValue).length;
         while (end - start > 1) {
             const mid = Math.floor((start + end) / 2);
             range.setStart(textNode, mid);
@@ -117,9 +140,16 @@ export class GoogleDocsUtil {
         return range;
     }
 
+    /**
+     * @param {CSSStyleDeclaration} style
+     * @param {string} propertyName
+     * @param {string} value
+     */
     static _setImportantStyle(style, propertyName, value) {
         style.setProperty(propertyName, value, 'important');
     }
 }
+
+/** @type {HTMLStyleElement|undefined} */
 // eslint-disable-next-line no-underscore-dangle
-GoogleDocsUtil._styleNode = null;
+GoogleDocsUtil._styleNode = void 0;