# @ljharb/through

> simplified stream construction

Latest version **2.3.14** (published 2025-02-08) · MIT license · 0 weekly downloads

## Install

```sh
npm install @ljharb/through
pnpm add @ljharb/through
yarn add @ljharb/through
bun add @ljharb/through
```

## Health

**Score 35/100 (D)** — status: maintenance-mode.

Positive: has types; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

Negative: stale; low maintenance score.

## Facts

| | |
|---|---|
| Version | 2.3.14 |
| Published | 2025-02-08 |
| First published | 2023-07-18 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | CommonJS |
| Node | >= 0.4 |
| Dependencies | 1 |
| Unpacked size | 32 KB |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 3 |
| Author | Dominic Tarr |
| Maintainers | ljharb |
| Keywords | stream, streams, user-streams, pipe |

## Links

- npm: https://www.npmjs.com/package/@ljharb/through
- Repository: https://github.com/ljharb/through
- Issues: https://github.com/ljharb/through/issues
- npm.io page: https://npm.io/package/@ljharb/through

## Dependencies (1)

- [call-bind](https://npm.io/package/call-bind.md) ^1.0.8

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## Recent versions

- 2.3.14 (latest) — 2025-02-08
- 2.3.13 — 2024-03-09
- 2.3.12 — 2024-01-25
- 2.3.11 — 2023-10-11
- 2.3.10 — 2023-10-11
- 2.3.9 — 2023-07-18

## README

# @ljharb/through <sup>[![Version Badge][npm-version-svg]][package-url]</sup>

*Note*: This package is a fork of https://npmjs.com/through, and builds off of it.

[![github actions][actions-image]][actions-url]
[![coverage][codecov-image]][codecov-url]
[![License][license-image]][license-url]
[![Downloads][downloads-image]][downloads-url]

[![npm badge][npm-badge-png]][package-url]

Easy way to create a `Stream` that is both `readable` and `writable`.

* Pass in optional `write` and `end` methods.
* `through` takes care of pause/resume logic if you use `this.queue(data)` instead of `this.emit('data', data)`.
* Use `this.pause()` and `this.resume()` to manage flow.
* Check `this.paused` to see current flow state. (`write` always returns `!this.paused`).

This function is the basis for most of the synchronous streams in [event-stream](http://github.com/dominictarr/event-stream).

``` js
var through = require('@ljharb/through')

through(function write(data) {
    this.queue(data) //data *must* not be null
  },
  function end () { //optional
    this.queue(null)
  })
```

Or, can also be used _without_ buffering on pause, use `this.emit('data', data)`,
and this.emit('end')

``` js
var through = require('@ljharb/through')

through(function write(data) {
    this.emit('data', data)
    //this.pause()
  },
  function end () { //optional
    this.emit('end')
  })
```

## Extended Options

You will probably not need these 99% of the time.

### autoDestroy=false

By default, `through` emits close when the writable
and readable side of the stream has ended.
If that is not desired, set `autoDestroy=false`.

``` js
var through = require('@ljharb/through')

//like this
var ts = through(write, end, {autoDestroy: false})
//or like this
var ts = through(write, end)
ts.autoDestroy = false
```

[package-url]: https://npmjs.org/package/@ljharb/through
[npm-version-svg]: https://versionbadg.es/ljharb/through.svg
[deps-svg]: https://david-dm.org/ljharb/through.svg
[deps-url]: https://david-dm.org/ljharb/through
[dev-deps-svg]: https://david-dm.org/ljharb/through/dev-status.svg
[dev-deps-url]: https://david-dm.org/ljharb/through#info=devDependencies
[npm-badge-png]: https://nodei.co/npm/@ljharb/through.png?downloads=true&stars=true
[license-image]: https://img.shields.io/npm/l/@ljharb/through.svg
[license-url]: LICENSE
[downloads-image]: https://img.shields.io/npm/dm/@ljharb/through.svg
[downloads-url]: https://npm-stat.com/charts.html?package=@ljharb/through
[codecov-image]: https://codecov.io/gh/ljharb/through/branch/main/graphs/badge.svg
[codecov-url]: https://app.codecov.io/gh/ljharb/through/
[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/ljharb/through
[actions-url]: https://github.com/ljharb/through/actions

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