Levellevel
Universal abstract-level database for Node.js and browsers. This is a convenience package that exports classic-level in Node.js and browser-level in browsers, making it an ideal entry point to start creating lexicographically sorted key-value databases.
:pushpin: Which module should I use? What is
abstract-level? Head over to the FAQ.
Usage
If you are upgrading: please see UPGRADING.md.
const { Level } = require('level')
// Create a database
const db = new Level('example', { valueEncoding: 'json' })
// Add an entry with key 'a' and value 1
await db.put('a', 1)
// Add multiple entries
await db.batch([{ type: 'put', key: 'b', value: 2 }])
// Get value of key 'a': 1
const value = await db.get('a')
// Iterate entries with keys that are greater than 'a'
for await (const [key, value] of db.iterator({ gt: 'a' })) {
console.log(value) // 2
}
TypeScript type declarations are included and cover the methods that are common between classic-level and browser-level. Usage from TypeScript requires generic type parameters.
ts
// Specify types of keys and values (any, in the case of json).
// The generic type parameters default to Level<string, string>.
const db = new Level<string, any>('./db', { valueEncoding: 'json' })
// All relevant methods then use those types
await db.put('a', { x: 123 })
// Specify different types when overriding encoding per operation
await db.get<string, string>('a', { valueEncoding: 'utf8' })
// Though in some cases TypeScript can infer them
await db.get('a', { valueEncoding: db.valueEncoding('utf8') })
// It works the same for sublevels
const abc = db.sublevel('abc')
const xyz = db.sublevel<string, any>('xyz', { valueEncoding: 'json' })
Install
With npm do:
npm install level
For use in browsers, this package is best used with browserify, webpack, rollup or similar bundlers. For a quick start, visit browserify-starter or webpack-starter.
Supported Platforms
At the time of writing, level works in Node.js 18+ and Electron 30+ on Linux, Mac OS and Windows, including any future Node.js and Electron release thanks to Node-API, including ARM platforms like Raspberry Pi and Android, as well as in Chromium, Firefox and Safari. For details, see Supported Platforms of classic-level and Browser Support of browser-level.
Binary keys and values are supported across the board.
API
The API of level follows that of abstract-level. For additional options and methods specific to classic-level or browser-level, please see their respective READMEs. The documentation below only covers the common constructor.
db = new Level(location[, options])
Create a new database or open an existing database. The location argument must be a directory path (relative or absolute) where LevelDB will store its files, or in browsers, the name of the IDBDatabase to be opened.
Contributing
Level/level is an OPEN Open Source Project. This means that:
Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.
See the Contribution Guide for more details.
Donate
Support us with a monthly donation on Open Collective and help us continue our work.