memoization Concept in JavaScript

Posted by Prabhukiran345 under JavaScript category on | Points: 40 | Views : 875
Memoization is an optimization technique that is used to improve the performance of a function by caching its return values so that it does not need to redo the potentially heavy computations next time it is called.

Note: Not all functions can be memoized; only referential transparent functions


Generally consider caliculating Fibonacci number.. general javascript code looks as:

function getFibonacci (num) {
if (num < 2) {
return num;
return getFibonacci(num - 1) + getFibonacci(num - 2);

alert(getFibonacci(10)); // => 55 (with 177 iterations)

But using Momorizing concept we can achieve it very simpley in less Iterations by declaring a cache array where we can store the already-calculated function values that were returned in previous calls.
Then, instead of invoking the function,we can return these values in subsequent calls to the function..

function getFibonacci (num) {
var cache = [];
var fib = function(value) {
if(value < 2 ) return value;
if( cache[value] ) return cache[value];

cache[value] = (fib(value -1)) + (fib(value-2));
return cache[value];

return fib(num);

alert(getFibonacci(10)); // => 55 (with 20 iterations)

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