# memdown

> An drop-in replacement for LevelDOWN that works in memory only

Latest version **6.1.1** (published 2021-10-02) · MIT license · 0 weekly downloads

> **Deprecated.** This package is deprecated.

## Install

```sh
npm install memdown
pnpm add memdown
yarn add memdown
bun add memdown
```

## Health

**Score 10/100 (F)** — status: deprecated.

Negative: deprecated.

## Facts

| | |
|---|---|
| Version | 6.1.1 |
| Published | 2021-10-02 |
| First published | 2013-03-18 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | separate (@types/memdown) |
| Module format | CommonJS |
| Node | >=10 |
| Dependencies | 5 |
| Unpacked size | 30.4 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 286 |
| Maintainers | vweevers, rvagg, ralphtheninja |
| Keywords | level, leveldb, leveldown, levelup, memory |

## Links

- npm: https://www.npmjs.com/package/memdown
- Repository: https://github.com/Level/memdown
- Issues: https://github.com/Level/memdown/issues
- npm.io page: https://npm.io/package/memdown

## Dependencies (5)

- [ltgt](https://npm.io/package/ltgt.md) ^2.2.0
- [buffer](https://npm.io/package/buffer.md) ^6.0.3
- [inherits](https://npm.io/package/inherits.md) ^2.0.1
- [abstract-leveldown](https://npm.io/package/abstract-leveldown.md) ^7.2.0
- [functional-red-black-tree](https://npm.io/package/functional-red-black-tree.md) ^1.0.1

## Recent versions

- 6.1.1 (latest) — 2021-10-02
- 6.1.0 — 2021-09-28
- 6.0.0 — 2021-04-10
- 5.1.0 — 2019-10-04
- 5.0.0 — 2019-08-18
- 4.1.0 — 2019-06-28
- 4.0.0 — 2019-03-29
- 3.0.0 — 2018-05-22
- 2.0.0 — 2018-02-11
- 1.4.1 — 2017-10-04
- 1.4.0 — 2017-09-30
- 1.3.1 — 2017-09-15
- 1.3.0 — 2017-09-15
- 1.2.7 — 2017-09-06
- 1.2.4 — 2016-11-20
- … 27 more at https://npm.io/package/memdown/versions

## README

# memdown

> In-memory [`abstract-leveldown`] store for Node.js and browsers.

[![level badge][level-badge]](https://github.com/Level/awesome)
[![npm](https://img.shields.io/npm/v/memdown.svg)](https://www.npmjs.com/package/memdown)
[![Node version](https://img.shields.io/node/v/memdown.svg)](https://www.npmjs.com/package/memdown)
[![Test](https://img.shields.io/github/workflow/status/Level/memdown/Test?label=test)](https://github.com/Level/memdown/actions/workflows/test.yml)
[![Coverage](https://img.shields.io/codecov/c/github/Level/memdown?label=&logo=codecov&logoColor=fff)](https://codecov.io/gh/Level/memdown)
[![Standard](https://img.shields.io/badge/standard-informational?logo=javascript&logoColor=fff)](https://standardjs.com)
[![Common Changelog](https://common-changelog.org/badge.svg)](https://common-changelog.org)
[![Donate](https://img.shields.io/badge/donate-orange?logo=open-collective&logoColor=fff)](https://opencollective.com/level)

## Example

_If you are upgrading: please see [`UPGRADING.md`](./UPGRADING.md)._

```js
const levelup = require('levelup')
const memdown = require('memdown')

const db = levelup(memdown())

db.put('hey', 'you', (err) => {
  if (err) throw err

  db.get('hey', { asBuffer: false }, (err, value) => {
    if (err) throw err
    console.log(value) // 'you'
  })
})
```

With `async/await`:

```js
await db.put('hey', 'you')
const value = await db.get('hey', { asBuffer: false })
```

Your data is discarded when the process ends or you release a reference to the store. Note as well, though the internals of `memdown` operate synchronously - [`levelup`] does not.

## Browser support

[![Sauce Test Status](https://app.saucelabs.com/browser-matrix/level-ci.svg)](https://app.saucelabs.com/u/level-ci)

## Data types

Keys and values can be strings or Buffers. Any other key type will be irreversibly stringified. The only exceptions are `null` and `undefined`. Keys and values of that type are rejected.

```js
const db = levelup(memdown())

db.put('example', 123, (err) => {
  if (err) throw err

  db.createReadStream({
    keyAsBuffer: false,
    valueAsBuffer: false
  }).on('data', (entry) => {
    console.log(typeof entry.key) // 'string'
    console.log(typeof entry.value) // 'string'
  })
})
```

If you desire non-destructive encoding (e.g. to store and retrieve numbers as-is), wrap `memdown` with [`encoding-down`]. Alternatively install [`level-mem`] which conveniently bundles [`levelup`], `memdown` and [`encoding-down`]. Such an approach is also recommended if you want to achieve universal (isomorphic) behavior. For example, you could have [`leveldown`] in a backend and `memdown` in the frontend.

```js
const encode = require('encoding-down')
const db = levelup(encode(memdown(), { valueEncoding: 'json' }))

db.put('example', 123, (err) => {
  if (err) throw err

  db.createReadStream({
    keyAsBuffer: false,
    valueAsBuffer: false
  }).on('data', (entry) => {
    console.log(typeof entry.key) // 'string'
    console.log(typeof entry.value) // 'number'
  })
})
```

## Snapshot guarantees

A `memdown` store is backed by [a fully persistent data structure](https://www.npmjs.com/package/functional-red-black-tree) and thus has snapshot guarantees. Meaning that reads operate on a snapshot in time, unaffected by simultaneous writes.

## Test

In addition to the regular `npm test`, you can test `memdown` in a browser of choice with:

```
npm run test-browser-local
```

To check code coverage:

```
npm run coverage
```

## Contributing

[`Level/memdown`](https://github.com/Level/memdown) 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](https://github.com/Level/community/blob/master/CONTRIBUTING.md) for more details.

## Big Thanks

Cross-browser Testing Platform and Open Source ♥ Provided by [Sauce Labs](https://saucelabs.com).

[![Sauce Labs logo](./sauce-labs.svg)](https://saucelabs.com)

## Donate

Support us with a monthly donation on [Open Collective](https://opencollective.com/level) and help us continue our work.

## License

[MIT](LICENSE)

[`abstract-leveldown`]: https://github.com/Level/abstract-leveldown

[`levelup`]: https://github.com/Level/levelup

[`encoding-down`]: https://github.com/Level/encoding-down

[`leveldown`]: https://github.com/Level/leveldown

[`level-mem`]: https://github.com/Level/mem

[level-badge]: https://leveljs.org/img/badge.svg

---
_Source: https://npm.io/package/memdown · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._