promise-readable

promise-readable

This module allows to convert Readable stream into its promisified version, which returns Promise object fulfilled when open, data, close, end or error events occurred.

Requirements

This module requires Node >= 4.

Installation

npm install promise-readable

Usage

constructor

const promiseReadable = new PromiseReadable(stream)

PromiseReadable object requires Readable object to work.

Example:

const { PromiseReadable } = require('promise-readable')
const { createReadStream } = require('fs')

const stream = createReadStream('/etc/hosts')
const promiseReadable = new PromiseReadable(stream)

Typescript:

import { PromiseReadable } from 'promise-readable'
import { createReadStream } from 'fs'

const stream = createReadStream('/etc/hosts')
const promiseReadable = new PromiseReadable(stream)

stream

const stream = promiseReadable.stream

Original stream object.

Example:

console.log(promiseReadable.stream.flags)

read

const chunk = await promiseReadable.read(chunkSize)

This method returns Promise which is fulfilled when stream can return one chunk (by read method or data event) or stream is ended (end event).

If stream2 API is available then additional argument size is accepted.

Example:

const chunk = await promiseReadable.read(1024)

Promise returns chunk data if something has been read or undefined value if it is an end of the stream.

Example:

for (let chunk; (chunk = await promiseReadable.read()) != null;) {
  console.log(chunk.length)
}
console.log('stream is ended')

readAll

const content = await promiseReadable.readAll()

This method returns Promise which is fulfilled when stream is ended or undefined value if stream is already ended. The content from the stream is buffered and then Promise returns this concatenated content.

once

const result = await promiseReadable.once(event)

This method returns Promise which is fulfilled when stream emits event. The result of this event is returned or undefined value if stream is already ended.

The promise will reject on error.

Example:

const fd = await promiseReadable.once('open')
promiseReadable.stream.pipe(process.stdout)

await promiseReadable.once('close')

promiseReadable.stream.on('data', chunk => console.log(chunk.length))
await promiseReadable.once('end')

await promiseReadable.once('error') // undefined if already ended or throws error

Promise

This module uses any-promise and any ES6 Promise library or polyfill is supported.

Ie. bluebird can be used as Promise library for this module, if it is registered before.

require('any-promise/register/bluebird')
const { PromiseReadable } = require('promise-readable')

License

Copyright (c) 2017 Piotr Roszatycki [e-mail]

MIT