js DOM的几个常用方法

<div id="div1">这是个测试</div>
<p class="acc">111</p>
<p class="dd">222</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 = 0; 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
    }