Calculate a color gradient in Javascript

Here is a simple Javascript class to calculate the percent of a gradient between two colors given the percent (as a float 0-1) and two colors. Uses functions from php.js.

Color = function() {
};

Color.hexdec = function(hex_string) {
    hex_string = (hex_string + '').replace(/[^a-f0-9]/gi, '');
    return parseInt(hex_string, 16);
}

Color.dechex = function(number) {
    if (number < 0) {
        number = 0xFFFFFFFF + number + 1;
    }
    return parseInt(number, 10).toString(16);
}

Color.pad = function(number, length) {
    var str = '' + number;
    while (str.length < length) {
        str = '0' + str;
    }
    return str;
}

Color.calcgrad = function(val, color1, color2) {

    if(!color1.match(/^#[0-9a-f]{6}/) || !color2.match(/^#[0-9a-f]{6}/)) return 'match err!';

    if (val > 1) {
        val = 1;
    }
    if (val < 0) {
        val = 0;
    }
    val = parseFloat(val);

    c1 = [Color.hexdec(color1.substr(1,2)), Color.hexdec(color1.substr(3,2)), Color.hexdec(color1.substr(5,2))];
    c2 = [Color.hexdec(color2.substr(1,2)), Color.hexdec(color2.substr(3,2)), Color.hexdec(color2.substr(5,2))];

    if (val < .5) {
        delta = [(c2[0] - c1[0]), (c2[1] - c1[1]), (c1[2] - c2[2])];
        arrColor = [c1[0] + ((delta[0] * val) * 2), c1[1] + ((delta[1] * val) * 2), c1[2] - ((delta[2] * val) * 2)];
    } else {
        delta = [(c1[0] - c2[0]), (c1[1] - c2[1]), (c1[2] - c2[2])];
        arrColor = [c1[0] - *(delta[0] * (val - .5)* * 2), c1[1] - *(delta[1] * (val - .5)* * 2), c1[2] - *(delta[2] * (val - .5)* * 2)];
    }
    return '#'+Color.pad(Color.dechex(arrColor[0]),2)+Color.pad(Color.dechex(arrColor[1]),2)+Color.pad(Color.dechex(arrColor[2]),2);
}