Prototype replace() Method

Syntax:

element.replace(html);

Here html can be either plain text, an HTML snippet or any JavaScript object which has a toString() method.

If it contains any <script> tags, these will be evaluated after element has been replaced.

NOTE: If no argument is provided, Element.replace will simply clear element of its content.

Return Value:

Returns the removed HTML element.

Example:

<html>
<head>
<title>Prototype examples</title>

<script type="text/javascript" 
   src="/javascript/prototype.js">
</script>
<script>

function showResult()
{

   $('first').replace('<ul id="favorite">' +
                          '<li>kiwi</li>' +
   		          '<li>banana</li>' +
   		          '<li>apple</li>' +
		       '</ul>');
 
}

</script>
</head>

<body">

  <p id="test">Click the button to see the result.</p>
  
  <div id="food">
  <div id="fruits">
    <p id="first">Kiwi, banana <em>and</em> apple.</p>
  </div>
  </div>

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

</body>
</html>

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