后面三个undefined是怎样输出来的
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<div id="box">
<ul>
<li>111</li>
<li>222</li>
<li>333</li>
<li>444</li>
<li>555</li>
</ul>
</div>
<script type="text/javascript">
var oUl = document.querySelector('ul');
for(var i in oUl.children){
document.write(oUl.children[i].innerHTML);//111222333444555undefinedundefinedundefined
}
</script>
</body>
</html>
Frank清zxf
2020/11/28 16:28- javascript
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