DOM firstChild firstElementChiled

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<script>
		window.onload = function(){
			var oUl = document.getElementById("ul1");
			//ie 6-8  高版本不支持
//			oUl.firstChild.style.background = "red";
			
			//高版本浏览器
//			oUl.firstElementChild.style.background = "red";

			//兼容写法
			if(oUl.firstElementChild)
			{
				oUl.firstElementChild.style.background = "red";
			}else{
				oUl.firstChild.style.background = "red";
			}
		}
	</script>
	<body>
		<ul id="ul1">
			<li>1</li>
			<li>2</li>
		</ul>
	</body>
</html>

　　lastChild lastElementChild nextSibling nextElementSibing previousSibling previousElementSibling 一样使用