Editing Comparison of memoization implementations

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Preparation code

Preparation code HTML (this will be inserted in the <body> of a valid HTML5 document in standards mode) (useful when testing DOM operations or including libraries)

<script>
  //memo6 - by @madrobby/thomas fuchs
  
  Function.prototype.cached = function(){
    var self = this, cache = {};
    return function(arg){
      if(arg in cache) {
        //console.log('Cache hit for '+arg);
        return cache[arg];
      } else {
        //console.log('Cache miss for '+arg);
        return cache[arg] = self(arg);
      }
    }
  }
  
  
  //memo1
  //underscore.js implem
  
  function memoize1(func, hasher) {
      var memo = {};
      hasher || (hasher = function(value){
        return value; //^this could be done better..surely..
      });
      return function() {
        var key = hasher.apply(this, arguments);
        return hasOwnProperty.call(memo, key) ? memo[key] : (memo[key] = func.apply(this, arguments));
      };
    };
  
  
  //memo2 - another variation with changes by @addyosmani
  //based on initial work by thejit
  //note: I'm aware of the perils of hanging the implem off
  //fn, just want to find out if this version performs much better
    function memoize2(fn) {
      return function () {
          var args = Array.prototype.slice.call(arguments),
              hash = "",
              i  = args.length;
          while(i--){
            hash += (Object.prototype.toString.call({}) == Object.prototype.toString.call(args[i])) ? JSON.stringify(args[i]) : args[i];
            fn.memoize = fn.memoize || {};
        } 
          return (hash in fn.memoize) ? fn.memoize[hash] : fn.memoize[hash] = fn.apply(this, args);
      };
  }
  
  //memo3 - unscriptables implem.
  function memoize3(func, context) {
      function memoizeArg (argPos) {
          var cache = {};
          return function () {
              if (argPos == 0) {
                  if (!(arguments[argPos] in cache)) {
                      cache[arguments[argPos]] = func.apply(context, arguments);
                  }
                  return cache[arguments[argPos]];
              }
              else {
                  if (!(arguments[argPos] in cache)) {
                      cache[arguments[argPos]] = memoizeArg(argPos - 1);
                  }
                  return cache[arguments[argPos]].apply(this, arguments);
              }
          }
      }
      // JScript doesn't grok the arity property, but uses length instead
      var arity = func.arity || func.length;
      return memoizeArg(arity - 1);
  }
  
  //memo4 - by stevenlevithan
  function memoize4(functor, expiration) {
  	var memo = {};
  	return function () {
  		var key = Array.prototype.join.call(arguments, "§");
  		if (key in memo)
  			return memo[key];
  		if (expiration)
  			setTimeout(function () {delete memo[key];}, expiration);
  		return memo[key] = functor.apply(this, arguments);
  	};
  }
  
  
  //memo5 - @gbradley
  
  function memoize5(fn){
  var lookup={};
  return function(){
  	var args=[].slice.call(arguments);
  	var key=JSON.stringify(args);
  	var result=lookup[key];
  	if (!result){
  		result=fn.apply(this,args);
  		lookup[key]=result;
  		}
  	return result;
  	};
  }
  
  //memo7 - as memo2 but with lookups localised to a closure and the declaration of fn.memoize moved outside the loop, by @GotNoSugarBaby
  function memoize7 ( fn )
  {
  	var sliceArray = Array.prototype.slice
  	    , stringifyJson = JSON.stringify
  	    , castAsObject = Object;
  	
  	fn.memoize = fn.memoize || {};
  
  	return function ()
  	{
  		var args = sliceArray.call(arguments)
  		    , hash = ""
  		    , i = args.length
  		    , currentArg = null
  		    , memoizedFn = fn.memoize;
  
  		while (i--)
  		{
  			currentArg = args[i];
  			hash += (currentArg === castAsObject(currentArg)) ?
  				stringifyJson(currentArg) 
  				: 
  				currentArg;
  		}
  
  		return (hash in memoizedFn) ? 
  			memoizedFn[hash] 
  			: 
  			memoizedFn[hash] = fn.apply( this , args );
  	};
  }
  
  function fib(x) {
      if(x < 2) return 1; else return fib(x-1) + fib(x-2);
  }
  
  
</script>

Include JavaScript libraries as follows: <script src="//cdn.ext/library.js"></script>

Define setup for all tests (variables, functions, arrays or other objects that will be used in the tests) (runs before each clocked test loop, outside of the timed code region) (e.g. define local test variables, reset global variables, clear canvas, etc.) (see FAQ)

Define teardown for all tests (runs after each clocked test loop, outside of the timed code region) (see FAQ)

Code snippets to compare

Test 1

Title

Async (check if this is an asynchronous test)

Code

var fibTest1 = memoize1(fib);
console.log(fibTest1(20),'test1-norm');

setTimeout(function(){
	console.log(fibTest1(20),'test1-memo');
}, 1000);

Test 2

Title

Async (check if this is an asynchronous test)

Code

var fibTest2 = memoize2(fib);
console.log(fibTest2(20),'test2-norm');

setTimeout(function(){
	console.log(fibTest2(20),'test2-memo');
}, 1000);

Test 3

Title

Async (check if this is an asynchronous test)

Code

var fibTest3 = memoize3(fib);
console.log(fibTest3(20),'test3-norm');

setTimeout(function(){
	console.log(fibTest3(20),'test3-memo');
}, 1000);

Test 4

Title

Async (check if this is an asynchronous test)

Code

var fibTest4 = memoize4(fib,1000);
console.log(fibTest4(20),'test4-norm');

setTimeout(function(){
	console.log(fibTest4(20),'test4-memo');
}, 1000);

Test 5

Title

Async (check if this is an asynchronous test)

Code

var fibTest5 = memoize5(fib);
console.log(fibTest5(20),'test5-norm');

setTimeout(function(){
	console.log(fibTest5(20),'test5-memo');
}, 1000);

Test 6

Title

Async (check if this is an asynchronous test)

Code

var fibTest6 = fib.cached();
console.log(fibTest6(20),'test6-norm');

setTimeout(function(){
	console.log(fibTest6(20),'test6-memo');
}, 1000);

Test 7

Title

Async (check if this is an asynchronous test)

Code

var fibTest7 = memoize7(fib);
console.log(fibTest7(20),'test7-norm');

setTimeout(function(){
	console.log(fibTest7(20),'test7-memo');
}, 1000);