1. document.querySlector()
2.document.querySlectorAll()
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>新增选择器</title>
<script type="text/javascript">
window.onload = function(){
var oDiv = document.querySelector('#div1');
alert(oDiv);
var aLi = document.querySelectorAll('.list li');
alert(aLi.length)
}
</script>
</head>
<body>
<div id="div1">
<ul class="list">
<li>1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
<li>6</li>
</ul>
</div>
</body>
</html>