277 lines
9.9 KiB
Markdown
277 lines
9.9 KiB
Markdown
<h1 align="center">
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<img width="250" src="https://rawgit.com/lukechilds/keyv/master/media/logo.svg" alt="keyv">
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<br>
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<br>
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</h1>
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> Simple key-value storage with support for multiple backends
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[](https://travis-ci.org/lukechilds/keyv)
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[](https://coveralls.io/github/lukechilds/keyv?branch=master)
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[](https://www.npmjs.com/package/keyv)
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[](https://www.npmjs.com/package/keyv)
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Keyv provides a consistent interface for key-value storage across multiple backends via storage adapters. It supports TTL based expiry, making it suitable as a cache or a persistent key-value store.
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## Features
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There are a few existing modules similar to Keyv, however Keyv is different because it:
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- Isn't bloated
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- Has a simple Promise based API
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- Suitable as a TTL based cache or persistent key-value store
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- [Easily embeddable](#add-cache-support-to-your-module) inside another module
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- Works with any storage that implements the [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) API
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- Handles all JSON types plus `Buffer`
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- Supports namespaces
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- Wide range of [**efficient, well tested**](#official-storage-adapters) storage adapters
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- Connection errors are passed through (db failures won't kill your app)
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- Supports the current active LTS version of Node.js or higher
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## Usage
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Install Keyv.
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```
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npm install --save keyv
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```
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By default everything is stored in memory, you can optionally also install a storage adapter.
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```
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npm install --save @keyv/redis
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npm install --save @keyv/mongo
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npm install --save @keyv/sqlite
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npm install --save @keyv/postgres
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npm install --save @keyv/mysql
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```
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Create a new Keyv instance, passing your connection string if applicable. Keyv will automatically load the correct storage adapter.
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```js
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const Keyv = require('keyv');
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// One of the following
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const keyv = new Keyv();
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const keyv = new Keyv('redis://user:pass@localhost:6379');
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const keyv = new Keyv('mongodb://user:pass@localhost:27017/dbname');
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const keyv = new Keyv('sqlite://path/to/database.sqlite');
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const keyv = new Keyv('postgresql://user:pass@localhost:5432/dbname');
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const keyv = new Keyv('mysql://user:pass@localhost:3306/dbname');
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// Handle DB connection errors
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keyv.on('error', err => console.log('Connection Error', err));
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await keyv.set('foo', 'expires in 1 second', 1000); // true
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await keyv.set('foo', 'never expires'); // true
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await keyv.get('foo'); // 'never expires'
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await keyv.delete('foo'); // true
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await keyv.clear(); // undefined
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```
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### Namespaces
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You can namespace your Keyv instance to avoid key collisions and allow you to clear only a certain namespace while using the same database.
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```js
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const users = new Keyv('redis://user:pass@localhost:6379', { namespace: 'users' });
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const cache = new Keyv('redis://user:pass@localhost:6379', { namespace: 'cache' });
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await users.set('foo', 'users'); // true
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await cache.set('foo', 'cache'); // true
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await users.get('foo'); // 'users'
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await cache.get('foo'); // 'cache'
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await users.clear(); // undefined
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await users.get('foo'); // undefined
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await cache.get('foo'); // 'cache'
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```
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### Custom Serializers
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Keyv uses [`json-buffer`](https://github.com/dominictarr/json-buffer) for data serialization to ensure consistency across different backends.
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You can optionally provide your own serialization functions to support extra data types or to serialize to something other than JSON.
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```js
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const keyv = new Keyv({ serialize: JSON.stringify, deserialize: JSON.parse });
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```
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**Warning:** Using custom serializers means you lose any guarantee of data consistency. You should do extensive testing with your serialisation functions and chosen storage engine.
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## Official Storage Adapters
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The official storage adapters are covered by [over 150 integration tests](https://travis-ci.org/lukechilds/keyv/jobs/260418145) to guarantee consistent behaviour. They are lightweight, efficient wrappers over the DB clients making use of indexes and native TTLs where available.
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Database | Adapter | Native TTL | Status
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---|---|---|---
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Redis | [@keyv/redis](https://github.com/lukechilds/keyv-redis) | Yes | [](https://travis-ci.org/lukechilds/keyv-redis) [](https://coveralls.io/github/lukechilds/keyv-redis?branch=master)
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MongoDB | [@keyv/mongo](https://github.com/lukechilds/keyv-mongo) | Yes | [](https://travis-ci.org/lukechilds/keyv-mongo) [](https://coveralls.io/github/lukechilds/keyv-mongo?branch=master)
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SQLite | [@keyv/sqlite](https://github.com/lukechilds/keyv-sqlite) | No | [](https://travis-ci.org/lukechilds/keyv-sqlite) [](https://coveralls.io/github/lukechilds/keyv-sqlite?branch=master)
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PostgreSQL | [@keyv/postgres](https://github.com/lukechilds/keyv-postgres) | No | [](https://travis-ci.org/lukechildskeyv-postgreskeyv) [](https://coveralls.io/github/lukechilds/keyv-postgres?branch=master)
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MySQL | [@keyv/mysql](https://github.com/lukechilds/keyv-mysql) | No | [](https://travis-ci.org/lukechilds/keyv-mysql) [](https://coveralls.io/github/lukechilds/keyv-mysql?branch=master)
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## Third-party Storage Adapters
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You can also use third-party storage adapters or build your own. Keyv will wrap these storage adapters in TTL functionality and handle complex types internally.
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```js
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const Keyv = require('keyv');
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const myAdapter = require('./my-storage-adapter');
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const keyv = new Keyv({ store: myAdapter });
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```
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Any store that follows the [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) api will work.
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```js
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new Keyv({ store: new Map() });
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```
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For example, [`quick-lru`](https://github.com/sindresorhus/quick-lru) is a completely unrelated module that implements the Map API.
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```js
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const Keyv = require('keyv');
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const QuickLRU = require('quick-lru');
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const lru = new QuickLRU({ maxSize: 1000 });
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const keyv = new Keyv({ store: lru });
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```
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The following are third-party storage adapters compatible with Keyv:
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- [quick-lru](https://github.com/sindresorhus/quick-lru) - Simple "Least Recently Used" (LRU) cache
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- [keyv-file](https://github.com/zaaack/keyv-file) - File system storage adapter for Keyv
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- [keyv-dynamodb](https://www.npmjs.com/package/keyv-dynamodb) - DynamoDB storage adapter for Keyv
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## Add Cache Support to your Module
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Keyv is designed to be easily embedded into other modules to add cache support. The recommended pattern is to expose a `cache` option in your modules options which is passed through to Keyv. Caching will work in memory by default and users have the option to also install a Keyv storage adapter and pass in a connection string, or any other storage that implements the `Map` API.
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You should also set a namespace for your module so you can safely call `.clear()` without clearing unrelated app data.
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Inside your module:
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```js
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class AwesomeModule {
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constructor(opts) {
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this.cache = new Keyv({
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uri: typeof opts.cache === 'string' && opts.cache,
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store: typeof opts.cache !== 'string' && opts.cache,
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namespace: 'awesome-module'
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});
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}
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}
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```
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Now it can be consumed like this:
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```js
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const AwesomeModule = require('awesome-module');
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// Caches stuff in memory by default
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const awesomeModule = new AwesomeModule();
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// After npm install --save keyv-redis
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const awesomeModule = new AwesomeModule({ cache: 'redis://localhost' });
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// Some third-party module that implements the Map API
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const awesomeModule = new AwesomeModule({ cache: some3rdPartyStore });
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```
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## API
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### new Keyv([uri], [options])
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Returns a new Keyv instance.
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The Keyv instance is also an `EventEmitter` that will emit an `'error'` event if the storage adapter connection fails.
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### uri
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Type: `String`<br>
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Default: `undefined`
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The connection string URI.
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Merged into the options object as options.uri.
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### options
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Type: `Object`
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The options object is also passed through to the storage adapter. Check your storage adapter docs for any extra options.
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#### options.namespace
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Type: `String`<br>
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Default: `'keyv'`
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Namespace for the current instance.
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#### options.ttl
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Type: `Number`<br>
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Default: `undefined`
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Default TTL. Can be overridden by specififying a TTL on `.set()`.
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#### options.serialize
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Type: `Function`<br>
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Default: `JSONB.stringify`
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A custom serialization function.
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#### options.deserialize
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Type: `Function`<br>
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Default: `JSONB.parse`
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A custom deserialization function.
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#### options.store
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Type: `Storage adapter instance`<br>
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Default: `new Map()`
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The storage adapter instance to be used by Keyv.
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#### options.adapter
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Type: `String`<br>
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Default: `undefined`
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Specify an adapter to use. e.g `'redis'` or `'mongodb'`.
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### Instance
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Keys must always be strings. Values can be of any type.
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#### .set(key, value, [ttl])
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Set a value.
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By default keys are persistent. You can set an expiry TTL in milliseconds.
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Returns `true`.
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#### .get(key)
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Returns the value.
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#### .delete(key)
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Deletes an entry.
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Returns `true` if the key existed, `false` if not.
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#### .clear()
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Delete all entries in the current namespace.
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Returns `undefined`.
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## License
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MIT © Luke Childs
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