How to use rgba color from theme customizer color picker

Why exactly you want to represent it in RGBA where A means alpha channel (I guess)

I mean, hex does not support transparency, so if you want to convert it to RGB, you just need to convert from hex to decimal

r = parseInt(hex.substring(0,2), 16);
g = parseInt(hex.substring(2,4), 16);
b = parseInt(hex.substring(4,6), 16);
result="rgba("+r+','+g+','+b+','+1+')';

taken from http://jsfiddle.net/ekinertac/3Evx5/1/

this just converts every hex digit to decimal value.