// source http://jsbin.com/tusehi

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JS Bin</title>
</head>
<body>

mix = function(src, target, mix) {
  return [Math.floor(target[0] + (src - target[0]) * mix), Math.floor(target[1] + (src - target[1]) * mix), Math.floor(target[2] + (src - target[2]) * mix)];
};

shade = function(target, m) {
  return mix(0, target, m);
};

tint = function(target, m) {
  return mix(255, target, m);
};

rgb = [255, 10, 10];

console.log(shade(rgb, 0.1));

console.log(tint(rgb, 0.1));

</script>

shade = (target, m) -> mix 0, target, m
tint = (target, m) -> mix 255, target, m

# Test
rgb = [
  255
  10
  10
]
console.log shade(rgb, 0.1)
console.log tint(rgb, 0.1)
</script></body>
</html>