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

<h1>通过 id 查找 HTML 元素</h1>

<p id="id01">Hello World!</p>
<p id="id02">Hello China!</p>
<p id="id03">Hello Shanghai!</p>

<p id="demo"></p>

<script>
var myElement = document.getElementById("id03");
document.getElementById("demo").innerHTML = "段落 id03 的文本是:" + myElement.innerHTML;
</script>

</body>
</html>
运行结果: