@emotion/weak-memoize

What is @emotion/weak-memoize?

The @emotion/weak-memoize package is designed for memoization, a programming technique used to speed up computer programs by storing the results of expensive function calls and returning the cached result when the same inputs occur again. Specifically, it uses weak references to keys for memoizing, which allows for the garbage collection of keys that are no longer in use, preventing potential memory leaks in applications.

What are @emotion/weak-memoize's main functionalities?

Memoization of functions with object arguments

This feature allows you to memoize functions that take objects as arguments. When you pass an object to the memoized function, it computes the result and caches it. Subsequent calls with an object that has the same reference will return the cached result instead of recomputing it.

const memoizedFunc = weakMemoize(arg => { return expensiveComputation(arg); });
const result = memoizedFunc({ key: 'value' });
// Calling memoizedFunc with the same argument will return the cached result without recomputing

Other packages similar to @emotion/weak-memoize

memoizee

Memoizee is a complete memoize/cache solution for JavaScript, offering features like max age, max size, and pre-fetching. It differs from @emotion/weak-memoize by providing a more extensive set of configuration options for caching, but it doesn't use weak references by default, which could lead to different memory usage characteristics.

lodash.memoize

lodash.memoize is a function provided by the popular Lodash library for memoizing computations. It's simpler and doesn't use weak references, which makes it less suitable for memoizing functions with objects that might go out of scope, potentially leading to memory leaks compared to @emotion/weak-memoize.

fast-memoize

fast-memoize is a high-performance, zero-dependency memoization library. While it focuses on speed and efficiency, it does not use weak references for its caching mechanism, which differentiates it from @emotion/weak-memoize in terms of garbage collection behavior.

README

@emotion/weak-memoize

A memoization function that uses a WeakMap

Install

yarn add @emotion/weak-memoize

Usage

Because @emotion/weak-memoize uses a WeakMap the argument must be a non primitive type, e.g. objects, functions, arrays and etc. The function passed to weakMemoize must also only accept a single argument.

import weakMemoize from '@emotion/weak-memoize'

let doThing = weakMemoize(({ someProperty }) => {
  return { newName: someProperty }
})

let obj = { someProperty: true }

let firstResult = doThing(obj)

let secondResult = doThing(obj)

firstResult === secondResult // true

let newObj = { someProperty: true }

let thirdResult = doThing(newObj)

thirdResult === firstResult // false