Fibonacci Memoization

fibProxy.js

function proxy(fn) {
    const cache = {};

    return function (arg) {
        // add function result to cache
        if (cache[arg] === undefined) cache[arg] = fn.call(this, arg);

        return cache[arg];
    }
}

function fib(n) {
    if (n < 2) return n;

    return fibProxy(n - 1) + fibProxy(n - 2);
}

// the cache setup
const fibProxy = proxy(fib);

const start = new Date().getTime();
console.log(`Successione di Fibonacci 78: ${fibProxy(78)}, Execution Time: ${new Date().getTime() - start} ms`);