Why doesn't backgroundColor=rgb(a,b,c) work?

Question

Answer 1

The problem is that the color needs to be a string:

var a = parseInt(prompt("Enter R"),10);
var b = parseInt(prompt("Enter G"),10);
var c = parseInt(prompt("Enter B"),10);
document.body.style.backgroundColor = "rgb(" + [a,b,c].join() + ")";

Demo