domtastic/src/dom/contains.js

Small, fast, and modular DOM and event library for modern browsers.

/**
 * @module contains
 */

/**
 * Test whether an element contains another element in the DOM.
 *
 * @param {Element} container The element that may contain the other element.
 * @param {Element} element The element that may be a descendant of the other element.
 * @return {Boolean} Whether the `container` element contains the `element`.
 * @example
 *     $.contains(parentElement, childElement); // true/false
 */

export const contains = (container, element) => {
  if(!container || !element || container === element) {
    return false;
  } else if(container.contains) {
    return container.contains(element);
  } else if(container.compareDocumentPosition) {
    return !(container.compareDocumentPosition(element) & Node.DOCUMENT_POSITION_DISCONNECTED);
  }
  return false;
};