WeakArrayMap is a WeakMap that treats different array instances that have the same items as equal keys (shallowEqual).
Values are set and retrieved in O(arr.length).
Useful for memoizing multiple arguments without losing WeakMap support.
Installation
npm install weak-array-map
Usage
const a = { 'a': 1 }
const b1 = { 'b': 1 }
const b2 = { 'b': 2 }
// new arrays create different entries in regular WeakMap
const weakMap = new WeakMap()
weakMap.set([a, b1], 'hello')
assert.notStrictEqual(weakMap.get([a, b1]), 'hello') // CACHE MISS
// new arrays do not affect caching in WeakArrayMap
const weakArrayMap = new WeakArrayMap()
weakArrayMap.set([a, b1], 'hello')
assert.strictEqual(weakArrayMap.get([a, b1]), 'hello') // CACHE HIT
// works with memoized arguments
const sum = ({ a }, { b }) => ({ a: a + 1, b: b + 1 })
const memoized = memoize(sum)
assert.deepStrictEqual(memoized(a, b1), { a: 2, b: 2 })
assert.deepStrictEqual(memoized(a, b2), { a: 2, b: 3 })
assert.strictEqual(memoized(a, b1), memoized(a, b1))
assert.strictEqual(memoized(a, b2), memoized(a, b2))API
constructor
new WeakMap()
set: (arr, value) => void
Sets a value at the given shallow-equal array key.
get: (arr) => any
Returns the value at the given shallow-equal array key.
has: (arr) => boolean
Returns true if there is a value stored at the given shallow-equal array key.
Limitations
- Does not support primitive array items