How did the wrapper access the element from the decorator function?

Question

JavaScript

How does the wrapper get access to the cache object from the decorator, if, here, it doesn’t smell like a closure,

function f(x) {
  return Math.random()*x;
}


function makeCaching(f) {
  var cache = {}; 

  return function(x) {
    if (!(x in cache)) {
      cache[x] = f.call(this, x);
    }
    return cache[x];
  };

}

f = makeCaching(f);

var a = f(1);
var b = f(1);
alert( a == b ); // true (значение закешировано)

b = f(2);
alert( a == b ); // false, другой аргумент => другое значение

Answer 1

here the closure already carries)
we call makeCaching and redefine the function f. makeCaching, when executed, returns a new function that has a cache in the closure, this function decides whether to call the original function f (which is also in the closure) or get the value from the cache object