In following example of code, I want to traverse the responseText object which consist the html code came from request_page.php file. In onSuccess event, i want to check whether < Div > with id 'ersDiv' has any errors posted in it.

new Request.HTML({
    url: 'request_page.php',
    onSuccess: function(responseText, responseXML) {
    // My expected code to handle responseText object
    alert(errorMessage);
    },
    onFailure: function() {  }
});

request_page.php file is like this :

<div align='center'><div id='ersDiv'>Page loaded with insufficient data</div></div>