<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script src="js/jquery-3.3.1.js" type="text/javascript"></script>
<script type="text/javascript">
$(function(){
var d=document.getElementById("one");
var $j=$("#one");
var $a=$(d);
console.log($a.html());
})
</script>
</head>
<body>
<h1 id="one">一级标题</h1>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<script src="js/jquery-3.3.1.js" type="text/javascript"></script>
<script>
$(function(){
var $j=$("h1");
var d=$j[0];
console.log(d.innerHTML);
var d=$j.get(0);
console.log(d.innerHTML);
})
</script>
</head>
<body>
<h1 id="one">一级标题</h1>
</body>
</html>