Function getUniqueElementID

src/prototype/dom/dom.js:3089–3097

(element)

  GLOBAL.Element.Storage = { UID: 1 };

  function getUniqueElementID(element) {
    if (element === window) return 0;

    // Need to use actual `typeof` operator to prevent errors in some
    // environments when accessing node expandos.
    if (typeof element._prototypeUID === 'undefined')
      element._prototypeUID = Element.Storage.UID++;
    return element._prototypeUID;
  }

  // In Internet Explorer, DOM nodes have a `uniqueID` property. Saves us
  // from inventing our own.