Javascript使用setAttribute更改HTML元素屬性方法

Javascript可以使用getElementsById setAttribute來做到跟改html元素屬性方法如下：

範例一

 
 
    document.getElementsById("images").setAttribute("width", "200"); 

 //執行結果 <img id="images" src="" width="200"></code></pre>
<h2>範例二</h2>
<pre><code><!DOCTYPE html>
<html>
<head>
<style>
    .democlass {
        color: red;
    }
</style>
</head>
<body>

<h1>Hello World</h1>

Click the button to add a class attribute with the value of "democlass" to the h1 element.

<button onclick="myFunction()">Try it</button>

<script>
    function myFunction() {
        document.getElementsByTagName("H1")[0].setAttribute("class", "democlass");
    }