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AI solution for JavaScript Coding Question on BFE.dev
14. Implement a general memoization function - `memo()`

Here's one possible solution:

function memo(func, resolver = (...args) => args.join('_')) {
  const cache = {};

  return function memoized(...args) {
    const key = resolver(...args);

    if (key in cache) {
      return cache[key];
    }

    const result = func.apply(this, args);
    cache[key] = result;

    return result;
  };
}

The memo function takes in two parameters:

  • func, which is the original function that we want to memoize.
  • resolver, which is an optional function that takes in the arguments to func as input, and returns a key to use for caching.

The memo function returns a new function that can be used in place of func. Within this new function, we first generate a cache key based on the arguments passed in, using the resolver function. We then check if the key is already in the cache - if so, we return the cached value, otherwise, we call the original func with the given arguments and cache the result.

Note that we're using the spread operator (...) to pass the arguments to the resolver function and to the original function call. We're also using Function.prototype.apply to call the original function with the spread-out arguments.

If no resolver function is provided, we default to using Array.from(arguments).join('_') as the key generator.

One thing to keep in mind is that this implementation uses an object (cache) to store the memoized results, so if we call memo() many times with different functions, or with different argument patterns for the same function, we could end up using a lot of memory. A more sophisticated implementation could use a map or a WeakMap to limit memory usage.