Memoization

Once an expensive function runs, it can rewrite itself with an optimized version.

Memoization is a technique similar to caching that takes advantage of

the fact that functions are just data.

var getElement = function() {



    console.log("creating element");

    var element = document.createElement("div");



    // ... Do a bunch of expensive operations



    // Now OVERWRITE this function with a SIMPLER VERSION

    getElement = function() {

        return element;

    };



    return element;

};

The first time getElement runs, it creates the element and runs a bunch
of code with it. Then it rewrites the getElement function to solely return the created element. This makes subsequent calls to getElement much quicker.

Source:  "The JavaScript PocketGuide" - Lenny Burdette 2010