src/helpers/webview-ime-focus-helpers.js


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module.exports.releaseDocumentFocus = () => {
  const element = document.createElement('span');
  document.body.appendChild(element);

  const range = document.createRange();
  range.setStart(element, 0);

  const selection = window.getSelection();
  selection.removeAllRanges();
  selection.addRange(range);
  selection.removeAllRanges();

  document.body.removeChild(element);
};

module.exports.claimDocumentFocus = () => {
  const { activeElement } = document;
  const selection = window.getSelection();

  let selectionStart;
  let selectionEnd;
  let range;

  if (activeElement) ({ selectionStart, selectionEnd } = activeElement);
  if (selection.rangeCount) range = selection.getRangeAt(0);

  const restoreOriginalSelection = () => {
    if (selectionStart >= 0 && selectionEnd >= 0) {
      activeElement.selectionStart = selectionStart;
      activeElement.selectionEnd = selectionEnd;
    } else if (range) {
      selection.addRange(range);
    }
  };

  exports.releaseDocumentFocus();
  window.requestAnimationFrame(restoreOriginalSelection);
};