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111 lines
2.6 KiB
111 lines
2.6 KiB
# quick-lru [](https://travis-ci.org/sindresorhus/quick-lru) [](https://coveralls.io/github/sindresorhus/quick-lru?branch=master) |
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> Simple [“Least Recently Used” (LRU) cache](https://en.m.wikipedia.org/wiki/Cache_replacement_policies#Least_Recently_Used_.28LRU.29) |
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Useful when you need to cache something and limit memory usage. |
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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`. |
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## Install |
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``` |
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$ npm install quick-lru |
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``` |
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## Usage |
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```js |
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const QuickLRU = require('quick-lru'); |
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const lru = new QuickLRU({maxSize: 1000}); |
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lru.set('🦄', '🌈'); |
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lru.has('🦄'); |
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//=> true |
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lru.get('🦄'); |
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//=> '🌈' |
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``` |
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## API |
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### new QuickLRU(options?) |
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Returns a new instance. |
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### options |
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Type: `object` |
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#### maxSize |
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*Required*\ |
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Type: `number` |
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The maximum number of items before evicting the least recently used items. |
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#### onEviction |
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*Optional*\ |
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Type: `(key, value) => void` |
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Called right before an item is evicted from the cache. |
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Useful for side effects or for items like object URLs that need explicit cleanup (`revokeObjectURL`). |
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### Instance |
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The instance is [`iterable`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Iteration_protocols) so you can use it directly in a [`for…of`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/for...of) loop. |
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Both `key` and `value` can be of any type. |
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#### .set(key, value) |
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Set an item. Returns the instance. |
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#### .get(key) |
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Get an item. |
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#### .has(key) |
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Check if an item exists. |
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#### .peek(key) |
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Get an item without marking it as recently used. |
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#### .delete(key) |
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Delete an item. |
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Returns `true` if the item is removed or `false` if the item doesn't exist. |
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#### .clear() |
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Delete all items. |
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#### .keys() |
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Iterable for all the keys. |
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#### .values() |
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Iterable for all the values. |
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#### .size |
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The stored item count. |
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--- |
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<div align="center"> |
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<b> |
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<a href="https://tidelift.com/subscription/pkg/npm-quick-lru?utm_source=npm-quick-lru&utm_medium=referral&utm_campaign=readme">Get professional support for this package with a Tidelift subscription</a> |
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</b> |
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<br> |
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<sub> |
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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. |
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</sub> |
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</div>
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