alternative

decorator.js

let worker = {
  slow(min, max) {
    return min + max; // scary CPU-hogger is assumed
  }
};

function cachingDecorator(fn){
  const makeKey = input => String(input);
  let cache = {};
  return function wrap(...args) {
    let key = makeKey(args);
    if(!cache[key]) {
      cache[key] = fn.apply(this, args);
    }
    return cache[key];
  }
}