I’m learning different implementations of the memoize function, and something is confusing me. Here is one version of the code:

_.memoize = function(func) {
    let cache = {};

    return function() {
      let arg = JSON.stringify(arguments); //arg is an stringified array
      if(!(arg in cache)) {
        cache[arg] = func.apply(this, arguments);
      }
      return cache[arg];
    };
  };

My understanding of cahce[arg] is that the cache object has a key of arg, or if it doesn’t, the function call of func.apply(this, arguments) becomes the property at an arg key. If arg is already a key in cache, than the function returns the property at cache[arg].

Ok, but isn’t arg an array with a string in it? Assigned to a stringified version of arguments? Or is it a super long, single string formed by JSON.stringify?

How are the different arguments accessed? To me, this seems like the cache has a single key of either an array or a long string. Which means the identity of the individual arguments would be lost in a single piece of data, and I don’t see how they are being accessed. I guess I would assume a for loop or forEach would loop through to access each argument, but that’s not happening, so I don’t really know how to read this.