Prototype empty() Method

Syntax:

element.empty;

Return Value:

If it finds that element is an empty one then it returns true otherwise false

Example:

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

function showResult(){
   if($('wallet').empty() ){
       alert( "Wallet is empty " );
   }
   if($('cart').empty() ){
       alert( "Cart is full" );
   }
}
</script>
</head>

<body>

   <p>Click the button to see the result.</p>

   <div id="wallet">     </div>
   <div id="cart">full!</div>

   <br />
   <input type="button" value="showResult" 
             onclick="showResult();"/>

</body>
</html>

In this example:

$('wallet').empty();
// -> true
$('cart').empty();
// -> false

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