js DOM的几个常用方法

 <div id="div1">这是个测试</div>
 <p class="acc"></p>
 <p class="dd"></p>

  //js DOM的几个常用方法

     //document.getElementById,
     // document.getElementsByTagName,
     // document.getElementsByClassName,
     // getAttribute,
     // setAttribute

     var div1 = document.getElementById("div1").innerHTML;
     console.log(div1);//output:这是个测试

     var pars = document.getElementsByTagName("p");
     for (var i = ; i < pars.length; i++) {
         var title = pars[i].getAttribute("class");
         if (title) {
             pars[i].setAttribute("class", "look");//修改class的值为look
             console.log(pars[i].getAttribute("class"));//output:look
         }
     }

     var cls = document.getElementsByClassName("look");
     for (i in cls) {
         console.log(cls[i].innerHTML);//111,222
     }