You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
71 lines
2.5 KiB
71 lines
2.5 KiB
# 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.
|