memoize.js - a faster JavaScript memoizer

memoize.js

/*
* memoize.js
* by @philogb and @addyosmani
* further optimizations by @mathias
* Released under an MIT license.
*/
function memoize( fn ) {  
    return function () {  
        var args = Array.prototype.slice.call(arguments),  
            hash = "",  
            i  = args.length;  
            toString = Object.prototype.toString,
            callEm = toString.call({}),
            currentArg=null;
        while(i--){  
          currentArg = args[i];
          hash += (callEm == toString.call(currentArg)) ?   
          JSON.stringify(currentArg) : currentArg;  
          fn.memoize || (fn.memoize || {});  
          //old: fn.memoize = fn.memoize || {};
      }   
        return (hash in fn.memoize) ? fn.memoize[hash] :   
        fn.memoize[hash] = fn.apply( this , args );  
    };  
}  
  

fn.memoize || (fn.memoize || {}); should be fn.memoize || (fn.memoize = {}); — sorry for the typo on IRC!

Thanks Mathias! :)

I beliwe that cache (memoize) object should be connected with result rather than with source function.
This way creating multiple memoized functions from thesame source function do not result in overlapping cache entries.

Ex.:

function(_thiz, _fn) { var _cache = undefined _cache = {}; var _r = (function(thiz, fn, cache){ return function() { var args = Array.prototype.slice.call(arguments), hash = "", i = args.length; currentArg = null; while (i--) { currentArg = args[i]; hash += (currentArg === Object(currentArg)) ? JSON.stringify(currentArg) : currentArg; } cache.repo || (cache.repo = {}) cache.clearCache = function() { cache.repo = {}; }; return (cache.repo.hasOwnProperty(hash)) ? cache.repo[hash] : cache.repo[hash] = fn.apply(thiz, args); }; })(_thiz, _fn, _cache) _r._cache = _cache; return _r; }