Prototype startsWith() Method

Syntax:

string.startsWith(substring);

Return Value:

Returns the boolean value.

Example:

<html>
<head>
<title>Prototype examples</title>
<script type="text/javascript" 
   src="/javascript/prototype.js">
</script>
<script>

function showResult(){

  var str = "Prototype JavaScript";
  alert ("First Check : " + str.startsWith("JavaScript") );
  alert ("Second Check : " + str.startsWith("Prototype") );

}

</script>
</head>

<body>

  <p>Click the button to see the result.</p>
  <br />
  <br />
  <input type="button" value="Result" onclick="showResult();"/>

</body>
</html>

To understand it in better way you can Try it yourself.