function getColorValues( color ){
	var values = { red:null, green:null, blue:null, alpha:null };
	if( typeof color == 'string' ){
		/* hex */
		if( color.indexOf('#') === 0 ){
			color = color.substr(1)
			if( color.length == 3 )
				values = {
					red:   parseInt( color[0]+color[0], 16 ),
					green: parseInt( color[1]+color[1], 16 ),
					blue:  parseInt( color[2]+color[2], 16 ),
					alpha: 1
				}
			else
				values = {
					red:   parseInt( color.substr(0,2), 16 ),
					green: parseInt( color.substr(2,2), 16 ),
					blue:  parseInt( color.substr(4,2), 16 ),
					alpha: 1
				}
		/* rgb */
		}else if( color.indexOf('rgb(') === 0 ){
			var pars = color.indexOf(',');
			values = {
				red:   parseInt(color.substr(4,pars)),
				green: parseInt(color.substr(pars+1,color.indexOf(',',pars))),
				blue:  parseInt(color.substr(color.indexOf(',',pars+1)+1,color.indexOf(')'))),
				alpha: 1
			}
		/* rgba */
		}else if( color.indexOf('rgba(') === 0 ){
			var pars = color.indexOf(','),
				repars = color.indexOf(',',pars+1);
			values = {
				red:   parseInt(color.substr(5,pars)),
				green: parseInt(color.substr(pars+1,repars)),
				blue:  parseInt(color.substr(color.indexOf(',',pars+1)+1,color.indexOf(',',repars))),
				alpha: parseFloat(color.substr(color.indexOf(',',repars+1)+1,color.indexOf(')')))
			}
		/* verbous */
		}else{
			var stdCol = { acqua:'#0ff',   teal:'#008080',   blue:'#00f',      navy:'#000080',
						   yellow:'#ff0',  olive:'#808000',  lime:'#0f0',      green:'#008000',
						   fuchsia:'#f0f', purple:'#800080', red:'#f00',       maroon:'#800000',
						   white:'#fff',   gray:'#808080',   silver:'#c0c0c0', black:'#000' };
			if( stdCol[color]!=undefined )
				values = getColorValues(stdCol[color]);
		}
	}
	return values
}

this function gets a parameter like an hex color (es: "#ffffff"), an abbreviated hex color (es: "#fff"), an rgb color (es: "rgb(255,255,255)") or an rgba color (es: "rgba(255,255,255,1)"), and returns an object containing the rgba values, like { red:x, green:y, blue:z, alpha:k  }.

get RGBA values as an object

javascript, object, color

JavaScript