57 lines
1.8 KiB
JavaScript
57 lines
1.8 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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/**
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* Get the text of the element parameter, as provided by the Selection API. We need to
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* rely on the Selection API as it mimics exactly what the user would have if they do a
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* selection using the mouse and copy it. `HTMLElement.textContent` and
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* `HTMLElement.innerText` follow a different codepath than user selection + copy.
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* They both have issues when dealing with whitespaces, and therefore can't be used to
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* have a reliable result.
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*
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* As the Selection API is exposed through the Window object, if we don't have a window
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* we fallback to `HTMLElement.textContent`.
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*
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* @param {HTMLElement} el: The element we want the text of.
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* @returns {String|null} The text of the element, or null if el is falsy.
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*/
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function getElementText(el) {
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if (!el) {
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return null;
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}
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// If we can, we use the Selection API to match what the user would get if they
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// manually select and copy the message.
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const doc = el.ownerDocument;
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const win = doc && doc.defaultView;
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if (!win) {
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return el.textContent;
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}
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// We store the current selected range and unselect everything.
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const selection = win.getSelection();
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const currentSelectedRange =
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!selection.isCollapsed && selection.getRangeAt(0);
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selection.removeAllRanges();
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// Then creates a range from `el`, and get the text content.
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const range = doc.createRange();
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range.selectNode(el);
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selection.addRange(range);
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const text = selection.toString();
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// Finally we revert the selection to what it was.
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selection.removeRange(range);
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if (currentSelectedRange) {
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selection.addRange(currentSelectedRange);
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}
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return text;
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}
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module.exports = {
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getElementText,
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};
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