streamiterator

streamiterator

Converts ReadableStream into AsyncIterator.

Using

With this module you can iterate over a nodejs stream (file, http response, etc) with a plain loop:

import streamiterator from "streamiterator"
import split from "split"

async function DoIt() {
	// iterate over lines in a file
	for await (const line of streamiterator(
		fs.createReadStream("data.txt").pipe(split())
	)) {
		console.log(`Read: ${line}`)
	}
}

As of August, 2017 you need smth like either babel or node.js 8.4.0 or higher with --harmony_async_iteration switch to be able to use for await operator.

A bit of code with iterables can be seen in tests.

It's possible to iterate without for await, though it is not so nice as using syntactic suger:

import streamiterator from "streamiterator"

async function DoIt(stream) {
	for (
		let done, value, iterator = streamiterator(stream);
		{done, value} = await iterator.next(), !done;
	) {
		console.log(`Read: ${value}`)
	}
}

If the stream emits an error, it will be thrown while looping. Wrap your loop in try..catch to deal with it.

If eventually streams will support async iteration natively then this module will just redirect iteration to that native mechanism. No overhead will be added.

Polyfill

But if you believe that writing streamiterator(...) everywhere is a bullshit, and in your world streams have to be iterable from the scratch right now, then you can import streamiterator/polyfill in the root of your project and iterate just on streams:

import "streamiterator/polyfill"
import fs from "fs"

async function DoIt() {
	for await (const data of fs.createReadStream("./data.txt")) {
		console.log(data)
	}
}

Note that you don't need to import streamiterator/polyfill in every file of your project. Just in the main.js or similar.

Contributing

Please contribute! All contributions are greatly appreciated no matter how small or large the contribution is. Whether it's a small grammar fix in the README, a huge bug fix, or just an issue report, you will be recognized as a 'Contributor' to this project.

Please, feel free to open an issue or email me to [e-mail] if you have any question.