Get css top value as number not as string?

Question

In jQuery you can get the top position relative to the parent as a number, but you can not get the css top value as a number if it was set in px.
Say I have th

Answer 1

A slightly more practical/efficient plugin based on Ivan Castellanos' answer (which was based on M4N's answer). Using || 0 will convert Nan to 0 without the testing step.

I've also provided float and int variations to suit the intended use:

jQuery.fn.cssInt = function (prop) {
    return parseInt(this.css(prop), 10) || 0;
};

jQuery.fn.cssFloat = function (prop) {
    return parseFloat(this.css(prop)) || 0;
};

Usage:

$('#elem').cssInt('top');    // e.g. returns 123 as an int
$('#elem').cssFloat('top');  // e.g. Returns 123.45 as a float

Test fiddle on http://jsfiddle.net/TrueBlueAussie/E5LTu/