JS: Memorisation Pattern

MemoizationPattern.js

// You can add custom properties to your functions at any time. One use case for custom
// properties is to cache the results (the return value) of a function, so the next time the
// function is called, it doesn’t have to redo potentially heavy computations. Caching the
// results of a function is also known as memoization.

var myFunc = function (param) {
    if (!myFunc.cache[param]) {
        var result = {};
        // ... expensive operation ...
        myFunc.cache[param] = result;
    }
    return myFunc.cache[param];
};
// cache storage
myFunc.cache = {};

// The function myFunc creates a property cache, accessible as
// usual via myFunc.cache. The cache property is an object (a hash) where the parameter
// param passed to the function is used as a key and the result of the computation is the
// value.