对对象的引用出现在对象未加载之前,顺序不对。<body>
<div id="c_21" style="cursor:pointer;margin:0px;border-spacing:0px;border:1px outset #6f6f8f;color:#ffcfcf;
background-color:#3f3f4f;padding:3px 20px 3px 20px;" tabindex="0">
Button
</div>
<script language="javascript">
var element = document.getElementById("c_21");
element.style.backgroundColor = "blue";
</script>
<div id="c_21" style="cursor:pointer;margin:0px;border-spacing:0px;border:1px outset #6f6f8f;color:#ffcfcf;
background-color:#3f3f4f;padding:3px 20px 3px 20px;" tabindex="0">
Button
</div>
<script language="javascript">
var element = document.getElementById("c_21");
element.style.backgroundColor = "blue";
</script>
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