devtools/client/webconsole/utils/clipboard.js

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 "use strict";
   6
   7 /**
   8  * Get the text of the element parameter, as provided by the Selection API. We need to
   9  * rely on the Selection API as it mimics exactly what the user would have if they do a
  10  * selection using the mouse and copy it. `HTMLElement.textContent` and
  11  * `HTMLElement.innerText` follow a different codepath than user selection + copy.
  12  * They both have issues when dealing with whitespaces, and therefore can't be used to
  13  * have a reliable result.
  14  *
  15  * As the Selection API is exposed through the Window object, if we don't have a window
  16  * we fallback to `HTMLElement.textContent`.
  17  *
  18  * @param {HTMLElement} el: The element we want the text of.
  19  * @returns {String|null} The text of the element, or null if el is falsy.
  20  */
  21 function getElementText(el) {
  22   if (!el) {
  23     return null;
  24   }
  25   // If we can, we use the Selection API to match what the user would get if they
  26   // manually select and copy the message.
  27   const doc = el.ownerDocument;
  28   const win = doc && doc.defaultView;
  29
  30   if (!win) {
  31     return el.textContent;
  32   }
  33
  34   // We store the current selected range and unselect everything.
  35   const selection = win.getSelection();
  36   const currentSelectedRange =
  37     !selection.isCollapsed && selection.getRangeAt(0);
  38   selection.removeAllRanges();
  39
  40   // Then creates a range from `el`, and get the text content.
  41   const range = doc.createRange();
  42   range.selectNode(el);
  43   selection.addRange(range);
  44   const text = selection.toString();
  45
  46   // Finally we revert the selection to what it was.
  47   selection.removeRange(range);
  48   if (currentSelectedRange) {
  49     selection.addRange(currentSelectedRange);
  50   }
  51
  52   return text;
  53 }
  54
  55 module.exports = {
  56   getElementText,
  57 };