gistfile1.js

Function.prototype.cache = function(){
  var _cache = {};

  // var key = function(args) {
  //   return 'x' + args.join('');
  // }

  var key = function(args) {
    var sig = 'x', index = args.length;
    while (index--) {
      sig += args[index].toString();
    }
    return sig;
  }

  this.store = function(args, value){
    _cache[key(args)] = value;
    return value;
  }

  this.fetch = function(args) {
    var k = key(args);
    if (k in _cache) {
      console.log('cached')
      return _cache[k];
    } else {
      return null;
    }
  }

  return this;
}();

var withCache = function(){
  var args = Array.prototype.slice.apply(arguments);
  if (withCache.cache.fetch(args) != null) {
    return withCache.cache.fetch(args);
  }

  var func = args.shift();
  var result = func.apply(this, args);
  return withCache.cache.store(args, result)
};

function sum() {
  var total = 0, length = arguments.length;
  while (length--) {
    total += arguments[length];
  }
  return total;
}

function sin(num) {
  return Math.sin(num)
}

// 524287, 9369319, 2147483647
function isPrime(num) {
  var prime = num != 1;
  for ( var i = 2; i < num; i++ ) {
    if ( num % i == 0 ) { 
      prime = false; 
      break; 
    } 
  }
  return prime;
}