Retrieve Button value with jQuery

A simple one, I'm trying to retrieve the value attribute of a button when its been pressed using jQuery, here's what I have:

<script type="text/javascript">
    $(document).ready(function() {
        $('.my_button').click(function() {
            alert($(this).val());
        });
    });
</script>

<button class="my_button" name="buttonName" value="buttonValue">
    Button Label</button>

In Firefox my alert displays 'buttonValue' which is great but in IE7 it displays 'Button Label'.

What jQuery should I use to always get the button's value? Or should I be using a different approach?

Many thanks.

ANSWER: I'm now using

<input class="my_button" type="image" src="whatever.png" value="buttonValue" />

As a button value is an attribute you need to use the .attr() method in jquery. This should do it

<script type="text/javascript">
    $(document).ready(function() {
        $('.my_button').click(function() {
            alert($(this).attr("value"));
        });
    });
</script>

You can also use attr to set attributes, more info in the docs.

This only works in JQuery 1.6+. See postpostmodern's answer for older versions.

I know this was posted a while ago, but in case anyone is searching for an answer and really wants to use a button element instead of an input element...

You can not use .attr('value') or .val() with a button in IE. IE reports both the .val() and .attr("value") as being the text label (content) of the button element instead of the actual value of the value attribute.

You can work around it by temporarily removing the button's label:

var getButtonValue = function($button) {
    var label = $button.text(); 
    $button.text('');
    var buttonValue = $button.val();
    $button.text(label);
    return buttonValue;
}

There are a few other quirks with buttons in IE. I have posted a fix for the two most common issues here.