<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟学堂(edu.jb51.net)</title>
</head>
<body>
<p id="demo">单击按钮显示负无穷大</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
var x=100;
var demo=document.getElementById("demo");
demo.innerHTML=x.NEGATIVE_INFINITY;
}
</script>
</body>
</html>