memoize.js

// Simple memoization, done

const memoize = (fn) => {
  const memo = {};
  return function(...args){
    const hash = JSON.stringify(args);
    if(hash in memo) return memo[hash];
    return fn(...args);
  };
};

const fib = (n) => (n < 2)? 1: fib(n-2) + fib(n-1);
const smart_fib = memoize((n) =>(n < 2)? 1: smart_fib(n-2) + smart_fib(n-1));

fib(100); // don't try, probably takes forevery
smart_fib(100); // yeah! quick and nice