text: // 渲染dom，解析指令
  function Compile(vm, el) {
      this.$vm = vm;
      el = this.$el = this.isElementNode(el) ? el: document.querySelector('el')
      if(!el) return
      this._update(el);
  }
  Compile.prototype = {
      _update: function (el) {
          this.$fragment = document.createDocumentFragment()
          this.createElm(el)
          el.appendChild(this.$fragment)
      },
  
      createElm: function (node) {
          var childNode = node.firstChild;
          if(childNode) {
              this.$fragment.appendChild(childNode)
              this.createElm(node)
          }
      }
  }
  