code: function switchTab( tabParentId ) {
      var tabElements = $G( tabParentId ).children,
          tabHeads = tabElements[0].children,
          tabBodys = tabElements[1].children;
  
      for ( var i = 0, length = tabHeads.length; i < length; i++ ) {
          var head = tabHeads[i];
          if ( head.className === "focus" )clickHandler(tabHeads,tabBodys, head );
          head.onclick = function () {
              clickHandler(tabHeads,tabBodys,this);
          }
      }
  }
docs: TAB切换
  @param tabParentId  tab的父节点ID或者对象本身