在线运行代码 - 菜鸟教程

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>菜鸟教程(cainiaoplay.com)</title>
</head>
<body>

<p id="p1">Click the button to locate where "locate" first occurs.</p>
<p id="p2">0</p>
<button onclick="myFunction()">点我</button>
<script>
function myFunction(){
	var str=document.getElementById("p1").innerHTML;
	var n=str.indexOf("locate");
	document.getElementById("p2").innerHTML=n+1;
}
</script>

</body>
</html>

源代码

动行结果