within-element/index.js

check if an element is within the element

/**
 * Check if the DOM element `child` is within the given `parent` DOM element.
 *
 * @param {DOMElement|Range} child - the DOM element or Range to check if it's within `parent`
 * @param {DOMElement} parent  - the parent node that `child` could be inside of
 * @return {Boolean} True if `child` is within `parent`. False otherwise.
 * @public
 */

module.exports = function within (child, parent) {
  // don't throw if `child` is null
  if (!child) return false;

  // Range support
  if (child.commonAncestorContainer) child = child.commonAncestorContainer;
  else if (child.endContainer) child = child.endContainer;

  // traverse up the `parentNode` properties until `parent` is found
  var node = child;
  while (node = node.parentNode) {
    if (node == parent) return true;
  }

  return false;
};