Why when we use Decorators we pass suppliers functions with it's parameters?

Question

here is a simple worker object and a caching decorator that add caching behaves to the object method(worker.slow) and hash used to make key for cache Map in cachingDecorator(func, hash).

let worker = {
  slow(min, max) {
    alert(`Called with ${min},${max}`);
    return min + max;
  }
};

function cachingDecorator(func, hash) { //here 
  let cache = new Map();
  return function() {
    let key = hash(arguments); // (*)
    if (cache.has(key)) {
      return cache.get(key);
    }

    let result = func.call(this, ...arguments); 

    cache.set(key, result);
    return result;
  };
}

function hash(args) {
  return args[0] + ',' + args[1];
}

worker.slow = cachingDecorator(worker.slow, hash); / * 
here why did we passed hash without useing it dirctly ? */

alert( worker.slow(3, 5) ); 
alert( "Again " + worker.slow(3, 5) ); 

i used it from outside like this and no different.

so i don't understand what is the different between these two codes if anyone can

explain it or give me a reference to understand.. thx in advanced.

let worker = {
  slow(min, max) {
    alert(`Called with ${min},${max}`);
    return min + max;
  }
};

function hash(args) {
  return args[0] + ',' + args[1];
}
  
function cachingDecorator(func) { // here 
  let cache = new Map();
  return function() {
    let key = hash(arguments); // (*)
    if (cache.has(key)) {
      return cache.get(key);
    }

    let result = func.call(this, ...arguments); 

    cache.set(key, result);
    return result;
  };
}


worker.slow = cachingDecorator(worker.slow); // here 

alert( worker.slow(3, 5) ); 
alert( "Again " + worker.slow(3, 5) );