即使元素存在，getElementById（）也会返回null
问题描述：
我试图用getElementById（）获取元素，但即使元素存在，它也会返回null。我做错了什么？
I'm trying to get the element with getElementById(), but it returns null even though the element exists. What am I doing wrong?
<html>
<head>
<title>blah</title>
<script type="text/javascript">
alert(document.getElementById("abc"));
</script>
</head>
<body>
<div id="abc">
</div>
</body>
答
你必须把它放在文档 load 事件中。在执行脚本时，DOM没有得到 abc 。
You have to put this in a document load event. The DOM hasn't gotten to abc by the time the script is executed.