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- # from2 [](https://flattr.com/submit/auto?user_id=hughskennedy&url=http://github.com/hughsk/from2&title=from2&description=hughsk/from2%20on%20GitHub&language=en_GB&tags=flattr,github,javascript&category=software)[](http://github.com/hughsk/stability-badges) #
-
- `from2` is a high-level module for creating readable streams that properly handle backpressure.
-
- Convience wrapper for
- [readable-stream](http://github.com/isaacs/readable-stream)'s `ReadableStream`
- base class, with an API lifted from
- [from](http://github.com/dominictarr/from) and
- [through2](http://github.com/rvagg/through2).
-
- ## Usage ##
-
- [](https://nodei.co/npm/from2)
-
- ### `stream = from2([opts], read)` ###
-
- Where `opts` are the options to pass on to the `ReadableStream` constructor,
- and `read(size, next)` is called when data is requested from the stream.
-
- * `size` is the recommended amount of data (in bytes) to retrieve.
- * `next(err)` should be called when you're ready to emit more data.
-
- For example, here's a readable stream that emits the contents of a given
- string:
-
- ``` javascript
- var from = require('from2')
-
- function fromString(string) {
- return from(function(size, next) {
- // if there's no more content
- // left in the string, close the stream.
- if (string.length <= 0) return next(null, null)
-
- // Pull in a new chunk of text,
- // removing it from the string.
- var chunk = string.slice(0, size)
- string = string.slice(size)
-
- // Emit "chunk" from the stream.
- next(null, chunk)
- })
- }
-
- // pipe "hello world" out
- // to stdout.
- fromString('hello world').pipe(process.stdout)
- ```
-
- ### `stream = from2.obj([opts], read)` ###
-
- Shorthand for `from2({ objectMode: true }, read)`.
-
- ### `createStream = from2.ctor([opts], read)` ###
-
- If you're creating similar streams in quick succession you can improve
- performance by generating a stream **constructor** that you can reuse instead
- of creating one-off streams on each call.
-
- Takes the same options as `from2`, instead returning a constructor which you
- can use to create new streams.
-
- ### See Also
-
- - [from2-array](https://github.com/binocarlos/from2-array) - Create a from2 stream based on an array of source values.
- - [from2-string](https://github.com/yoshuawuyts/from2-string) - Create a stream from a string. Sugary wrapper around from2.
-
- ## License ##
-
- MIT. See [LICENSE.md](http://github.com/hughsk/from2/blob/master/LICENSE.md) for details.
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