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Universalabstract-level database for Node.js and browsers. This is a convenience package that exportsclassic-level in Node.js andbrowser-level in browsers, making it an ideal entry point to start creating lexicographically sorted key-value databases.

📌 Which module should I use? What isabstract-level? Head over to theFAQ.

If you are upgrading: please seeUPGRADING.md.

const{ Level}=require('level')// Create a databaseconstdb=newLevel('example',{valueEncoding:'json'})// Add an entry with key 'a' and value 1awaitdb.put('a',1)// Add multiple entriesawaitdb.batch([{type:'put',key:'b',value:2}])// Get value of key 'a': 1constvalue=awaitdb.get('a')// Iterate entries with keys that are greater than 'a'forawait(const[key,value]ofdb.iterator({gt:'a'})){console.log(value)// 2}

TypeScript type declarations are included and cover the methods that are common betweenclassic-level andbrowser-level. Usage from TypeScript requires generic type parameters.

// Specify types of keys and values (any, in the case of json).// The generic type parameters default to Level<string, string>.constdb=newLevel<string,any>('./db',{valueEncoding:'json'})// All relevant methods then use those typesawaitdb.put('a',{x:123})// Specify different types when overriding encoding per operationawaitdb.get<string,string>('a',{valueEncoding:'utf8'})// Though in some cases TypeScript can infer themawaitdb.get('a',{valueEncoding:db.valueEncoding('utf8')})// It works the same for sublevelsconstabc=db.sublevel('abc')constxyz=db.sublevel<string,any>('xyz',{valueEncoding:'json'})

Withnpm do:

npm install level

For use in browsers, this package is best used withbrowserify,webpack,rollup or similar bundlers. For a quick start, visitbrowserify-starter orwebpack-starter.

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 toNode-API, including ARM platforms like Raspberry Pi and Android, as well as in Chromium, Firefox and Safari. For details, seeSupported Platforms ofclassic-level andBrowser Support ofbrowser-level.

Binary keys and values are supported across the board.

The API oflevel follows that ofabstract-level. For additional options and methods specific toclassic-level orbrowser-level, please see their respective READMEs. The documentation below only covers the common constructor.

Create a new database or open an existing database. Thelocation argument must be a directory path (relative or absolute) where LevelDB will store its files, or in browsers, the name of theIDBDatabase to be opened.

Level/level is anOPEN 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 theContribution Guide for more details.

Support us with a monthly donation onOpen Collective and help us continue our work.

MIT