Function cloneNode

01.GettingStarted/js/vue.js:3603–3642

* 1. Deal with Safari cloning nested bug by * manually cloning all template instances. * 2. Deal with IE10/11 textarea placeholder bug by setting * the correct value after cloning. * * @param {Element|DocumentFragment} node * @return {Element|DocumentFragment}

(node)

   */

  function cloneNode(node) {
    /* istanbul ignore if */
    if (!node.querySelectorAll) {
      return node.cloneNode();
    }
    var res = node.cloneNode(true);
    var i, original, cloned;
    /* istanbul ignore if */
    if (hasBrokenTemplate) {
      var tempClone = res;
      if (isRealTemplate(node)) {
        node = node.content;
        tempClone = res.content;
      }
      original = node.querySelectorAll('template');
      if (original.length) {
        cloned = tempClone.querySelectorAll('template');
        i = cloned.length;
        while (i--) {
          cloned[i].parentNode.replaceChild(cloneNode(original[i]), cloned[i]);
        }
      }
    }
    /* istanbul ignore if */
    if (hasTextareaCloneBug) {
      if (node.tagName === 'TEXTAREA') {
        res.value = node.value;
      } else {
        original = node.querySelectorAll('textarea');
        if (original.length) {
          cloned = res.querySelectorAll('textarea');
          i = cloned.length;
          while (i--) {
            cloned[i].value = original[i].value;
          }
        }
      }
    }
    return res;
  }

  /**
   * Process the template option and normalizes it into a