Memoize filer.

[Serhioromano]

You have code like this.

var fromCache = cache[key];
if (fromCache) {
  return fromCache;
}

I think this will not work good if service(colback) that uses it return empty array. It will trigger that service again. The fact that there is nothing in cache[key] does not mean that this was never called before.

My be I am wrong.

[m59peacemaker]

@Serhioromano oops! That was careless on my part. Empty arrays evaluate as truthy, but you are correct that I failed to handle cases where the function returns falsy values, like '' or null, etc. I have pushed the correction.

    if (cache.hasOwnProperty(key)) {
      return cache[key];
    }

[Serhioromano]

Ok, good. I see ad61550.

Thank you. Good staff by the way.