How to convert “background-color” to rgb() format?

Question

Here is my problem:

I want to change the opacity of background-color of one of the elements on my page. in order to do this I need to first convert the color to rgb() fo

Answer 1

This function will get you the r and g and b that you can use to create any format you want:

color_1 = resolve_color('#FFCC00');

color_2 = resolve_color('#FC0');

color_3 = resolve_color('rgb(255, 204, 0)');

color_4 = resolve_color('rgb(100%, 80%, 0%)');

In all examples, color_N is:

/* color_N is an array
 *   - color_N['red']    : 255
 *   - color_N['greenn'] : 204
 *   - color_N['red']    : 0
 */

Function

function resolve_color(color){
    // return an array containing R, G and B values
    if(color === 'transparent')// IE (6 and ?)
        color = '#FFF';
    var r,g,b;
    var hex_color_pcre = new RegExp("^#[0-9a-f]{3}([0-9a-f]{3})?$",'gi');
    var rgb_color_pcre = new RegExp("rgb\\(\\s*((?:[0-2]?[0-9])?[0-9])\\s*,\\s*((?:[0-2]?[0-9])?[0-9])\\s*,\\s*((?:[0-2]?[0-9])?[0-9])\\s*\\)$",'gi');
    var rgb_percent_color_pcre = new RegExp("rgb\\(\\s*((?:[0-1]?[0-9])?[0-9])%\\s*,\\s*((?:[0-1]?[0-9])?[0-9])%\\s*,\\s*((?:[0-1]?[0-9])?[0-9])%\\s*\\)$",'gi');
    if(color.match(hex_color_pcre)){
        if(color.length == 4){
            r  = color.charAt(1)+""+color.charAt(1);
            g  = color.charAt(2)+""+color.charAt(2);
            b  = color.charAt(3)+""+color.charAt(3);
        }
        else{
            r  = color.charAt(1)+""+color.charAt(2);
            g  = color.charAt(3)+""+color.charAt(4);
            b  = color.charAt(5)+""+color.charAt(6);
        }
        r = h2d(r);
        g = h2d(g);
        b = h2d(b);
    }
    else if(color.match(rgb_color_pcre)){
        r = RegExp.$1;
        g = RegExp.$2;
        b = RegExp.$3;
    }
    else if(color.match(rgb_percent_color_pcre)){
        r = parseInt((RegExp.$1)*2.55);
        g = parseInt((RegExp.$2)*2.55);
        b = parseInt((RegExp.$3)*2.55);
    }
    else
        return false;

    var returned =[];
    returned['red'] = r;
    returned['green'] = g;
    returned['blue'] = b;
    return returned;
}

function h2d(h) {
    // hex to decimal
    return parseInt(h,16);
} 

source: http://www.kadimi.com/en/javascript-tween-function-368