Function getOffsets

docs/external/js/react-dom.development.js:6847–6877

* @param {DOMElement} outerNode * @return {?object}

(outerNode)

   */

  function getOffsets(outerNode) {
    var ownerDocument = outerNode.ownerDocument;
    var win = ownerDocument && ownerDocument.defaultView || window;
    var selection = win.getSelection && win.getSelection();

    if (!selection || selection.rangeCount === 0) {
      return null;
    }

    var anchorNode = selection.anchorNode,
        anchorOffset = selection.anchorOffset,
        focusNode = selection.focusNode,
        focusOffset = selection.focusOffset; // In Firefox, anchorNode and focusNode can be "anonymous divs", e.g. the
    // up/down buttons on an <input type="number">. Anonymous divs do not seem to
    // expose properties, triggering a "Permission denied error" if any of its
    // properties are accessed. The only seemingly possible way to avoid erroring
    // is to access a property that typically works for non-anonymous divs and
    // catch any error that may otherwise arise. See
    // https://bugzilla.mozilla.org/show_bug.cgi?id=208427

    try {
      /* eslint-disable no-unused-expressions */
      anchorNode.nodeType;
      focusNode.nodeType;
      /* eslint-enable no-unused-expressions */
    } catch (e) {
      return null;
    }

    return getModernOffsetsFromPoints(outerNode, anchorNode, anchorOffset, focusNode, focusOffset);
  }
  /**
   * Returns {start, end} where `start` is the character/codepoint index of
   * (anchorNode, anchorOffset) within the textContent of `outerNode`, and