Partial Application in Javascript

partial-application.js

function partial(fn) {
   var __slice = Array.prototype.slice,
      args = __slice.call(arguments, 1);

   return function () {
      return fn.apply(this, args.concat(__slice.call(arguments)));
   };
}

function multiply(a, b) {
   return a * b;
}

var times2 = partial(multiply, 2),
    times3 = partial(multiply, 3);

   
console.assert(times2(2) === 4, "2 * 2 = 4");
console.assert(times2(3) === 6, "2 * 3 = 6");

console.assert(times3(2) === 6, "3 * 2 = 6");
console.assert(times3(3) === 9, "3 * 3 = 9");