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https://github.com/kt3k/through1
:one::aquarius::one: A simple utility for creating 1 to 1 transform stream.
https://github.com/kt3k/through1
gulp nodejs stream transform
Last synced: 8 days ago
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:one::aquarius::one: A simple utility for creating 1 to 1 transform stream.
- Host: GitHub
- URL: https://github.com/kt3k/through1
- Owner: kt3k
- License: mit
- Created: 2018-02-24T14:01:35.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2018-02-25T02:39:55.000Z (almost 7 years ago)
- Last Synced: 2025-01-11T20:22:29.229Z (about 1 month ago)
- Topics: gulp, nodejs, stream, transform
- Language: JavaScript
- Homepage:
- Size: 9.77 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# :one::aquarius::one: through1 v1.0.1
[](https://circleci.com/gh/kt3k/through1)
[](https://codecov.io/gh/kt3k/through1)
> A simple utility for creating 1 to 1 transform stream.
# :cd: Install
Via npm:
npm i through1
# Motivation
In the the most use cases, transforms are 1 to 1 transform, which means that it generates one output for each input. The official transform constructor is too complex for this usage. It has the following signature:
```js
new Transform({
transform (chunk, enc, cb) {
...
}
})
```
This supports one to N transform, where N is 0, 1, 2, or any arbitrary positive integer. This is too much for 1 to 1 transform.
`through1` provides simpler interface for creating 1 to 1 transform.
# :memo: Usage
```js
const through1 = require('through1')
```
If you transform the input **synchronously**, then return the transformed output:
```js
// byte stream
// synchronous transform
through1((chunk, enc) => myTransformFunc(chunk, enc))
```
If you work on the **object mode** stream (for example, like [gulp][]'s stream), then use `.obj` shorthand:
```js
// object stream
// synchronous transform
through1.obj(file => myTransformFunc(func))
```
## Asynchronous use case
If your transformation is asynchronous, then return the promise:
```js
// byte stream
// asynchronous transform
through1((chunk, enc) => myTransformPromise(chunk, enc))
```
If you work on **object mode**:
```js
// object stream
// asynchronous transform
through1.obj(file => myTransformPromise(file))
```
# Comparison
| | through1 | [map-stream][] | [gulp-map][]
|-------------------------|----------|----------------|--------------
| object mode support | ✅ | ✅ | ✅
| non object mode support | ✅ | ✅ | ❌
| promise support | ✅ | ❌ | ✅
| stream version | stream 2 | stream 1 | stream 2
| back-pressure support | ✅ | ❌ | ✅
| dependencies | 0 | 0 | [9](https://gist.github.com/kt3k/4cab6a63514381027f47046572d8d7ec)
# License
MIT
[through2]: https://npm.im/through2
[gulp]: https://npm.im/gulp
[map-stream]: https://npm.im/map-stream
[gulp-map]: https://npm.im/gulp-map