Custom cache object to be used with Re-reselect. It utilizes a Weak Map so that both the cache key object and selectorFn can be garbage collected.
import createCachedSelector from 're-reselect';
import { FlatWeakMapCache } from 're-reselect-flat-weak-map-cache';
createCachedSelector()({
// ...
keySelector,
cacheObject: new FlatWeakMapCache()
});See example for full usage.
By default, only allows string or number cache keys. It does provide a few custom cache objects that will allow any type as a cache key. These objects, like FlatMapCache, utilize a Map.
The downside with using a Map is that any object you use as a key and its associated selectorFn will not be garbage collected. Even if the object used as a key is no longer referenced in the application.
While this likely won't be an issue for most applications, the associated memory leaks could be a problem for memory intensive applications.
I've provided an example to illustrate a use case you've probably seen in Redux applications.
To follow best practices, objects are treated as immutable: any change to an object should yield a new object, not mutate the original. If that object is used as a cache key, each iteration of the object will not be able to be garbage collected. And each selectorFn associated with that key will not be garbage collected.
Conversely, a weak map holds a weak reference to the key object. So if there are no other references to the object, it and its value will be garbage collected.
- patrick-steele-idem - identified the problem with memory leaks using caching selectors
- Publish to NPM
- Add another cache object that will handle a key that can be a primitive type as well (weak maps don't allow primitive types)
- This is my first NPM package, and I may not have followed best practices, so I plan to follow this tutorial to improve this package structure
- More descriptive errors when attempting to use a primitive type as a key