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