Prototype compact() Method

Syntax:

array.compact()  ;

Return Value:

Returns an new array without any null of undefined values.

Example:

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

function showResult(){

   var oldArr =['Sam','Justin','Andrew','Dan', null, undefined];
   alert("Guys in old Arr" );
   oldArr.each(function(item) {
      alert(item );
   });
   var newArr = oldArr.compact();
   alert("Guys in new Arr" );
   newArr.each(function(item) {
      alert(item );
   });

}

</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.