forked from Fediversity/fediversity.eu
140 lines
3.6 KiB
Markdown
140 lines
3.6 KiB
Markdown
# quick-lru [](https://travis-ci.org/sindresorhus/quick-lru) [](https://coveralls.io/github/sindresorhus/quick-lru?branch=master)
|
|
|
|
> 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`.
|
|
|
|
## Install
|
|
|
|
```
|
|
$ npm install quick-lru
|
|
```
|
|
|
|
## Usage
|
|
|
|
```js
|
|
const QuickLRU = require('quick-lru');
|
|
|
|
const lru = new QuickLRU({maxSize: 1000});
|
|
|
|
lru.set('🦄', '🌈');
|
|
|
|
lru.has('🦄');
|
|
//=> true
|
|
|
|
lru.get('🦄');
|
|
//=> '🌈'
|
|
```
|
|
|
|
## API
|
|
|
|
### new QuickLRU(options?)
|
|
|
|
Returns a new instance.
|
|
|
|
### options
|
|
|
|
Type: `object`
|
|
|
|
#### maxSize
|
|
|
|
*Required*\
|
|
Type: `number`
|
|
|
|
The maximum number of items before evicting the least recently used items.
|
|
|
|
#### maxAge
|
|
|
|
Type: `number`\
|
|
Default: `Infinity`
|
|
|
|
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.
|
|
|
|
#### onEviction
|
|
|
|
*Optional*\
|
|
Type: `(key, value) => void`
|
|
|
|
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`).
|
|
|
|
### Instance
|
|
|
|
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.
|
|
|
|
Both `key` and `value` can be of any type.
|
|
|
|
#### .set(key, value, options?)
|
|
|
|
Set an item. Returns the instance.
|
|
|
|
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(key)
|
|
|
|
Get an item.
|
|
|
|
#### .has(key)
|
|
|
|
Check if an item exists.
|
|
|
|
#### .peek(key)
|
|
|
|
Get an item without marking it as recently used.
|
|
|
|
#### .delete(key)
|
|
|
|
Delete an item.
|
|
|
|
Returns `true` if the item is removed or `false` if the item doesn't exist.
|
|
|
|
#### .clear()
|
|
|
|
Delete all items.
|
|
|
|
#### .resize(maxSize)
|
|
|
|
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.
|
|
|
|
#### .keys()
|
|
|
|
Iterable for all the keys.
|
|
|
|
#### .values()
|
|
|
|
Iterable for all the values.
|
|
|
|
#### .entriesAscending()
|
|
|
|
Iterable for all entries, starting with the oldest (ascending in recency).
|
|
|
|
#### .entriesDescending()
|
|
|
|
Iterable for all entries, starting with the newest (descending in recency).
|
|
|
|
#### .size
|
|
|
|
The stored item count.
|
|
|
|
---
|
|
|
|
<div align="center">
|
|
<b>
|
|
<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>
|
|
</b>
|
|
<br>
|
|
<sub>
|
|
Tidelift helps make open source sustainable for maintainers while giving companies<br>assurances about security, maintenance, and licensing for their dependencies.
|
|
</sub>
|
|
</div>
|