Simple “Least Recently Used” (LRU) cache. 

Simple “Least Recently Used” (LRU) cache

sindresorhus

quick-lru

export interface Options<KeyType, ValueType> {

	The maximum number of milliseconds an item should remain in the cache.

	By default, `maxAge` will be `Infinity`, which means that items will never expire.

	Lazy expiration upon the next write or read call.

	Individual expiration of an item can be specified by the `set(key, value, maxAge)` method.

	The maximum number of items before evicting the least recently used items.

	Called right before an item is evicted from the cache.

	Useful for side effects or for items like object URLs that need explicit cleanup (`revokeObjectURL`).

	onEviction?: (key: KeyType, value: ValueType) => void;

export default class QuickLRU<KeyType, ValueType> implements Iterable<[KeyType, ValueType]> {

export default class QuickLRU<KeyType, ValueType> extends Map implements Iterable<[KeyType, ValueType]> {

	Simple ["Least Recently Used" (LRU) cache](https://en.m.wikipedia.org/wiki/Cache_replacement_policies#Least_Recently_Used_.28LRU.29).

	The instance is an [`Iterable`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Iteration_protocols) of `[key, value]` pairs so you can use it directly in a [`for…of`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/for...of) loop.

	const lru = new QuickLRU({maxSize: 1000});

	constructor(options: Options<KeyType, ValueType>);

	[Symbol.iterator](): IterableIterator<[KeyType, ValueType]>;

	Individual expiration of an item can be specified with the `maxAge` option. If not specified, the global `maxAge` value will be used in case it is specified in the constructor, otherwise the item will never expire.

	set(key: KeyType, value: ValueType, options?: {maxAge?: number}): this;

	@returns The stored item or `undefined`.

	get(key: KeyType): ValueType | undefined;

	Get an item without marking it as recently used.

	peek(key: KeyType): ValueType | undefined;

	@returns `true` if the item is removed or `false` if the item doesn't exist.

	Update the `maxSize` in-place, discarding items as necessary. Insertion order is mostly preserved, though this is not a strong guarantee.

	Useful for on-the-fly tuning of cache sizes in live systems.

	Iterable for all entries, starting with the oldest (ascending in recency).

	entriesAscending(): IterableIterator<[KeyType, ValueType]>;

	Iterable for all entries, starting with the newest (descending in recency).

	entriesDescending(): IterableIterator<[KeyType, ValueType]>;

export default class QuickLRU extends Map {

		if (!(options.maxSize && options.maxSize > 0)) {

			throw new TypeError('`maxSize` must be a number greater than 0');

		if (typeof options.maxAge === 'number' && options.maxAge === 0) {

			throw new TypeError('`maxAge` must be a number greater than 0');

		// TODO: Use private class fields when ESLint supports them.

		this.maxAge = options.maxAge || Number.POSITIVE_INFINITY;

	// TODO: Use private class methods when targeting Node.js 16.

		if (typeof this.onEviction !== 'function') {

		if (typeof item.expiry === 'number' && item.expiry <= Date.now()) {

			if (typeof this.onEviction === 'function') {

		const deleted = this._deleteIfExpired(key, item);

		return item.expiry ? this._getOrDeleteIfExpired(key, item) : item.value;

				const deleted = this._deleteIfExpired(key, value);

	forEach(callbackFunction, thisArgument = this) {

		for (const [key, value] of this.entriesAscending()) {

			callbackFunction.call(thisArgument, value, key, this);

		return JSON.stringify([...this.entriesAscending()]);

	"description": "Simple “Least Recently Used” (LRU) cache",

	"funding": "https://github.com/sponsors/sindresorhus",

# quick-lru [![Coverage Status](https://codecov.io/gh/sindresorhus/quick-lru/branch/main/graph/badge.svg)](https://codecov.io/gh/sindresorhus/quick-lru/branch/main)

> Simple [“Least Recently Used” (LRU) cache](https://en.m.wikipedia.org/wiki/Cache_replacement_policies#Least_Recently_Used_.28LRU.29)

Useful when you need to cache something and limit memory usage.

Inspired by the [`hashlru` algorithm](https://github.com/dominictarr/hashlru#algorithm), but instead uses [`Map`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Map) to support keys of any type, not just strings, and values can be `undefined`.

const lru = new QuickLRU({maxSize: 1000});

It's a [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) subclass.

The maximum number of items before evicting the least recently used items.

The maximum number of milliseconds an item should remain in cache.

By default maxAge will be Infinity, which means that items will never expire.

Lazy expiration happens upon the next `write` or `read` call.

Individual expiration of an item can be specified by the `set(key, value, options)` method.

Called right before an item is evicted from the cache.

Useful for side effects or for items like object URLs that need explicit cleanup (`revokeObjectURL`).

The instance is an [`Iterable`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Iteration_protocols) of `[key, value]` pairs so you can use it directly in a [`for…of`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/for...of) loop.

Both `key` and `value` can be of any type.

Individual expiration of an item can be specified with the `maxAge` option. If not specified, the global `maxAge` value will be used in case it is specified on the constructor, otherwise the item will never expire.

Get an item without marking it as recently used.

Returns `true` if the item is removed or `false` if the item doesn't exist.

Update the `maxSize`, discarding items as necessary. Insertion order is mostly preserved, though this is not a strong guarantee.

Useful for on-the-fly tuning of cache sizes in live systems.

Iterable for all entries, starting with the oldest (ascending in recency).

Iterable for all entries, starting with the newest (descending in recency).

Iterable for all entries, starting with the newest (ascending in recency).

**This method exists for `Map` compatibility. Prefer [.entriesAscending()](#entriesascending) instead.**

#### .forEach(callbackFunction, thisArgument)

Loop over entries calling the `callbackFunction` for each entry (ascending in recency).

- [yocto-queue](https://github.com/sindresorhus/yocto-queue) - Tiny queue data structure

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		Tidelift helps make open source sustainable for maintainers while giving companies<br>assurances about security, maintenance, and licensing for their dependencies.

		@@ -27,3 +27,3 @@ export interface Options<KeyType, ValueType> {

		export default class QuickLRU<KeyType, ValueType> implements Iterable<[KeyType, ValueType]> {
		export default class QuickLRU<KeyType, ValueType> extends Map implements Iterable<[KeyType, ValueType]> {
		/**
		@@ -30,0 +30,0 @@ The stored item count.

		@@ -1,3 +0,5 @@
		export default class QuickLRU {
		export default class QuickLRU extends Map {
		constructor(options = {}) {
		super();

		if (!(options.maxSize && options.maxSize > 0)) {
		@@ -265,2 +267,16 @@ throw new TypeError('`maxSize` must be a number greater than 0');
		}

		entries() {
		return this.entriesAscending();
		}

		forEach(callbackFunction, thisArgument = this) {
		for (const [key, value] of this.entriesAscending()) {
		callbackFunction.call(thisArgument, value, key, this);
		}
		}

		[Symbol.toStringTag]() {
		return JSON.stringify([...this.entriesAscending()]);
		}
		}

		{
		"name": "quick-lru",
		"version": "6.0.2",
		"version": "6.1.0",
		"description": "Simple “Least Recently Used” (LRU) cache",
		@@ -5,0 +5,0 @@ "license": "MIT",

		@@ -37,2 +37,4 @@ # quick-lru [![Coverage Status](https://codecov.io/gh/sindresorhus/quick-lru/branch/main/graph/badge.svg)](https://codecov.io/gh/sindresorhus/quick-lru/branch/main)

		It's a [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) subclass.

		### options
		@@ -126,2 +128,14 @@

		#### .entries()

		Iterable for all entries, starting with the newest (ascending in recency).

		This method exists for `Map` compatibility. Prefer [.entriesAscending()](#entriesascending) instead.

		#### .forEach(callbackFunction, thisArgument)

		Loop over entries calling the `callbackFunction` for each entry (ascending in recency).

		This method exists for `Map` compatibility. Prefer [.entriesAscending()](#entriesascending) instead.

		#### .size
		@@ -128,0 +142,0 @@

Improved metrics