<![CDATA[<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>W3C菜鸟教程(w3cdata.com)</title>
</head>
<body>
<p>假设 y=5，计算 x=y+2，并显示结果。</p>
<button onclick="myFunction()">点击这里</button>
<p id="demo"></p>
<script>
function myFunction(){
var y=5;
var x=y+2;
var demoP=document.getElementById("demo");
demoP.innerHTML="x=" + x;
}
</script>
</body>
</html>]]>