An optimization used to speed up consecutive function calls by caching the result of calls with identical input.

Here is an example of a memoizer function, taken from the book JavaScript The Good Parts by Douglas Crockford, that caches the results from a fibonacci number generator function:

var memoizer = function (memo, formula) {
  var recur = function (n) {
    var result = memo[n];
      if (typeof result !== 'number') {
        result = formula(recur, n);
        memo[n] = result;
      return result;
  return recur;

var fibonacci = memoizer([0, 1], function (recur, n) {
  return recur(n  1) + recur(n  2);


NPM Memoize Modules