判断单击还是双击

document.getElementById("google").onclick = function(){
      var link = this.href;
      if(this.clickTimeout){
          // 双击
          clearTimeout(this.clickTimeout);
          this.clickTimeout = null;
          alert(link);
      }
      else{
          // 单击
          var elem = this;
          this.clickTimeout = setTimeout(function(){
              // 跳转到相应网址
              elem.clickTimeout = null;
              window.location.href = link;
          }, 250);
      }
      //阻止链接onclick时的默认行为
      return false;
  };