Later Mom?

You know when you were a kid and mom told you to clean your room,
when you was busy with something else, your answer would always be the same: 'later, mom'.

This library is the universal 0 dependencies lazy cache implementation,
leveraging usage of es6 data structures.

Installation

yarn add @pietal.dev/cache --save

Usage

1const { Cache } = require("@pietal.dev/cache")
2
3const maxSize = 2 // will limit max cache size upon cache.get()
4const getUser = async (id) => {
5  const response = await fetch("https://dummyjson.com/users/" + id)
6  const { firstName, lastName, address } = await response.json()
7
8  return {
9    id,
10    name: `${firstName} ${lastName}`,
11    address,
12  }
13}
14
15const usersCached = new Cache(getUser, maxSize)
16
17Promise.all([
18  usersCached.get(1),
19  usersCached.get(2),
20  usersCached.get(3),
21  usersCached.get(4),
22]).then((users) => {
23  console.log(usersCached.data) // contains only last maxSize users (3 and 4)
24  console.log(usersCached.size) // 2
25})

1const { Cache } = require("@pietal.dev/cache")
2// create cache with factory function (may take any number of parameters)
3const cache = new Cache(() => Math.random())
4
5// each time you call the cache.get with same parameters
6// you will get the same once lazy cached answer
7const a = cache.get(1, 2, 3)
8const b = cache.get(1, 2, 3) // this will return the same as above
9const c = cache.get(1, 2)
10const d = cache.get(1, 2, 4)
11
12console.log(a === b) // true
13console.log(a !== c) // true
14console.log(a !== d) // true

API

1class Cache<T = unknown> {
2  constructor(factoryFunction: (...args: any[]) => T, maxSize: number = Infinity) {
3    //
4  }
5}

• creates a LaterMom (Lazy Map) instance with factory function for lazy cache

methods

• get(...args: any[]): T - get entry at key created from args, lazy instantiated by factory
• createKey(...args: any[]): string - creates string key
• create(...args: any[]): T - wrapped factory function
• hasKey(key: string): boolean - check if has entry at key
• has(...args: any[]): boolean - check if has entry at key created from args
• deleteKey(key: string): boolean - deletes entry from data at key
• delete(...args): boolean - deletes entry from data at key created from args
• size: number - returns size of data
• maxSize: number - on insert the oldest items are deleted until reached maxSize

properties:

• data: Map

Tests

1$ jest
2 PASS  ./index.test.js
3  ✓ Calls factory once when asked for same key many times (62 ms)
4  ✓ Getter is able to handle multiple arguments
5  ✓ Readme has working code (1 ms)
6
7Test Suites: 1 passed, 1 total
8Tests:       3 passed, 3 total
9Snapshots:   0 total
10Time:        0.946 s, estimated 1 s
11Ran all test suites.
12Done in 1.44s.

License

MIT

Author

Jacek Pietal @ 2019-2021