rgbHex.js

window.rgbHex = (function() {
    function isNumeric(arg) {
      return !isNaN(parseFloat(arg)) && isFinite(arg);
    }

    function trim(arg) {
        return arg.replace(/^\s+|\s+$/g, "");
    }

    function isRgb(arg) {
        arg = trim(arg);
        return isNumeric(arg) && arg >= 0 && arg <= 255;
    }
    
    function isHex(arg) {
        return /^[0-9a-f]{3}$|^[0-9a-f]{6}$/i.test(trim(arg));
    }

    function rgbToHex(arg) {
        arg = parseInt(arg, 10).toString(16);
        return arg.length === 1 ? '0' + arg : arg; 
    }

    function hexToRgb(arg) {
        return parseInt(arg, 16).toString();
    }

    function processRgb(arg) {
        arg = arg.split(',');

        if ( (arg.length === 3 || arg.length === 4) && isRgb(arg[0]) && isRgb(arg[1]) && isRgb(arg[2]) ) {
            if(arg.length === 4 && !isNumeric(arg[3])) { return null; }
            return '#' + rgbToHex(arg[0]).toUpperCase() + rgbToHex(arg[1]).toUpperCase() + rgbToHex(arg[2]).toUpperCase();
        }
        else {
            return null;
        }
    }

    function processHex(arg) {
        if(isHex(arg)) {
			// Error?? If you have this: FEA wouldn't this make FEAFEA and should this be FFEEAA?
            if(arg.length === 3) { arg = arg + arg; }

            return 'rgb(' + hexToRgb(arg.substr(0,2)) + ',' + hexToRgb(arg.substr(2,2)) + ',' + hexToRgb(arg.substr(4,2)) + ')';
        }
    }

    return function(arg) {        
        if(!arg) { return null; }

        var code = null,
			rgbRegex = /^rgba?\((.*)\);?$/,
			hexRegex = /^#/;
			
        arg = trim(arg.toString());
		
		if( rgbRegex.test(arg) )
		{
			return processRgb(arg.match(rgbRegex)[1]);
		}
        else if (hexRegex.test(arg)) {
            return processHex(arg.split('#').reverse()[0]);
        }
        //try to parse the string without rgb or #
        else {
            code = arg.split(',');

            if (code.length === 1) { return processHex(arg); }
            else if (code.length === 3 || code.length === 4) { return processRgb(arg); }
        }
    };
})();

if(jQuery) {
    jQuery.extend({
        rgbHex: function(arg) { return window.rgbHex(arg); }
    });
}