Weird addition with javascript in internet explorer

I'm having an issue in Internet Explorer 8, it's not computing addition of three variables in javascript?

I have this:

var y = function(s) {
    var p = ($.browser.msie || $.browser.opera) ? h(s) :  s.match(/^rgb\((\d+),\s*(\d+),\s*(\d+)\)$/);
    delete p[0];
    var r = ((p[1] / 255) * 0.2989);
    var g = ((p[2] / 255) * 0.5180);
    var b = ((p[3] / 255) * 0.1140);
    return (r + g + b);
};

Now, this is working in Chrome, Opera, and Firefox but not Internet Explorer, IE is giving me NaN. It's working if I just use return (r + g) or return (g + b)

I have tried return ((r + g) + b) and I have tried var rg = (r + g); return (rg + b);

But I keep getting NaN. Is there some special trick to开发者_StackOverflow社区 adding three variables in javascript with IE???

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I'd first try running isNaN() against each of the variables r,g and b to ensure that the value of each is in fact numeric. If so, perhaps try adding them together and assigning the result to a variable that you then return.