<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<style type="text/css"></style>
<script type="text/javascript">
window.onload = function () {
var oUl = document.getElementById("ul1");
if (oUl.firstElementChild) {
//谷歌浏览器
oUl.firstElementChild.style.background = "red";
}
if (oUl.firstChild) {
//IE 浏览器
oUl.firstChild.style.background = "red";
}
}
</script>
</head>
<body>
<ul id="ul1">
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
</body>
</html>
IE 有firstChild所以是true，相反的，谷歌没有，会返回undifined