App下載
實(shí)例代碼( Tip: 登錄后體驗(yàn)更佳 )
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>W3Cschool教程(w3cschool.cn)</title>
<style>
div {
    border: 1px solid black;
    margin: 5px;
}
</style>
</head>
<body>
<div id="myDIV"> 
  <p class="child"> div 元素中 class="child" 的 p </p>
  <p class="child"> div 元素中 class="child" 的另外一个 p </p>
  <p>在 div 中的 p 元素插入 <span class="child">class="child" 的 span 元素</span> 。</p>
</div>
<p>点击按钮为 id="myDIV" 的 div 元素中所有 class="child" 元素添加背景颜色。 </p>
<button onclick="myFunction()">点我</button>
<p><strong>注意:</strong> Internet Explorer 8 及更早 IE 版本不支持 getElementsByClassName() 方法。</p>
<script>
function myFunction() {
    var x = document.getElementById("myDIV");
    var y = x.getElementsByClassName("child");
    var i;
    for (i = 0; i < y.length; i++) {
        y[i].style.backgroundColor = "red";
    }
}
</script>
</body>
</html>
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
運(yùn)行結(jié)果