gistfile1.txt

var Math2 = function() {
  function sin(num) {
    console.log('Compute');
    return Math.sin(num);
  }
  
  return {
    sin: sin
  }
}();

function noArgs() {
  return 'no args';
}

function lotOfArgs(arg1, arg2, arg3) {
  return 'args: ' + arg1 + ' ' + arg2 + ' ' + arg3;
}

Function.prototype.cached = function() {
  var originalFunction = this, args = arguments;
  return (function() {
    if (args.length != 1)
      return originalFunction();

    if (originalFunction.cache == undefined)
      originalFunction.cache = {};
    var arg = args[0];
    if (originalFunction.cache[arg] == null)
      originalFunction.cache[arg] = originalFunction(arg);
    return originalFunction.cache[arg];
  })();
}


console.log(Math2.sin.cached(1));
console.log(Math2.sin.cached(0.5));
console.log(Math2.sin.cached(1));
console.log(noArgs());
console.log(lotOfArgs(1, 2, 3));