Function Composition in Javascript

function_composition.coffee

comp = (fns...) ->
  (arg) ->
    fns.reverse().reduce((x, fn) ->
      fn(x)
    , arg)

timesthree = (a) -> a * 3
timestwo = (a) -> a * 2
negative = (a) -> -a

composed = comp(timesthree, timestwo, negative)
console.log composed(10)

function_composition.js

function comp() {
  var fns = [].slice.apply(arguments);
  return function(arg) {
    return fns.reverse().reduce(function(x, fn) { return fn(x); }, arg);
  };
}

function timesthree(a) {
  return a * 3;
}

function timestwo(a) {
  return a * 2;
}

function negative(a) {
  return -a;
}

var composed = comp(timesthree, timestwo, negative);
console.log(composed(10)) // -60