代码示例:(标识:eg_js_intro_lightbulb)
<!DOCTYPE html>
<html>
<body>

<h2>JavaScript 能做什么?</h2>

<p>JavaScript 能够改变 HTML 属性值。</p>

<p>在本例中,JavaScript 改变了图像的 src 属性值。</p>

<button onclick="document.getElementById('myImage').src='/static/demo/images/eg_bulbon.gif'">开灯</button>

<img id="myImage" border="0" src="/static/demo/images/eg_bulboff.gif" style="text-align:center;">

<button onclick="document.getElementById('myImage').src='/static/demo/images/eg_bulboff.gif'">关灯</button>

</body>
</html>
运行结果: