JavaScript functional wrapping experiment

fn-wrapping.js

// doing some functional wrapping as a proof-of-concept for extensibility

var multiply = (function createMultiplier(invokeFn) {
  var invoke = invokeFn || function (a, b) {
    return a * b;
  };

  return {
    wrap: function (fn) {
      return createMultiplier(fn(invoke));
    },
    invoke: invoke
  };
})();

var logit = function (innerFn) {
  return function () {
    var startMillis = +new Date();
    var result = innerFn.apply(null, arguments);
    var endMillis = +new Date();
    console.log('Multiplication into %s took %s ms', result, (endMillis - startMillis));
    return result;
  };
};

var timesTwo = function (innerFn) {
  return function () {
    return innerFn.apply(null, arguments) * 2;
  };
};

// one might visualize the callchain as logit(timesTwo(originalMultiplyFn(2, 3)))
console.log(multiply.wrap(timesTwo).wrap(logit).invoke(2, 3));
// $ node fn-wrapping.js
// Multiplication into 12 took 1 ms
// 12 

// for inspiration:
// - https://github.com/briancavalier/aop-s2gx-2013/blob/master/src/aop-simple.js
// - http://blakeembrey.com/articles/wrapping-javascript-functions/