regex javascript to match both RGB and RGBA

Question

Currently I have this regex which matches to an RGB string. I need it enhanced so that it is robust enough to match either RGB or RGBA.

rgbRegex = /^rgb((d+),s*(d+),s*(d+))$/; //matches RGB

http://jsfiddle.net/YxU2m/

var rgbString =  "rgb(0, 70, 255)";
var RGBAString = "rgba(0, 70, 255, 0.5)";

var rgbRegex = /^rgb((d+),s*(d+),s*(d+))$/;
//need help on this regex
//I figure it needs to be ^rgba?, and then also an optional clause to handle the opacity

var partsRGB = rgbString.match(rgbRegex);
var partsRGBA = RGBAString.match(rgbRegex);

console.log(partsRGB); //["rgb(0, 70, 255)", "0", "70", "255"]
console.log(partsRGBA); //null. I want ["rgb(0, 70, 255, 0.5)", "0", "70", "255", "0.5"] 

Answer 1

Will this do?

var rgbRegex = /^rgba?((d+),s*(d+),s*(d+)(?:,s*(d+(?:.d+)?))?)$/