Package Exports

awaitify-stream

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (awaitify-stream) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

node-awaitify-stream

Read or write to a stream using while and await, not event handlers.

Requirements

Node v8+ recommended. async/await support was added in Node v7. Node v6 will throw SyntaxError: Unexpected token function for the examples below.

Install

npm install awaitify-stream

Read functions

readAsync([size]): Promise wrapper around readable.read. Returns a promise for the next chunk of data. Resolves to null at the end of the stream.

Write functions

writeAsync(chunk[, encoding]): Promise wrapper around writable.write. Returns a promise that resolves following a drain event (if necessary) and a call to write. Doesn't wait for the supplied chunk to be flushed.
endAsync([chunk][, encoding]): Promise wrapper around writable.end. Returns a promise that resolves when the stream is finished.

Reader/Writer API

Use createReader, createWriter or createDuplexer to get a wrapper around the stream.

const fs = require('fs');
const aw = require('awaitify-stream');

async function run() {
    let readStream = fs.createReadStream('firstExample.js');
    let reader = aw.createReader(readStream);
    let writer = aw.createWriter(process.stdout);

    // Read the file and write it to stdout.
    let chunk;
    while (null !== (chunk = await reader.readAsync())) {
        // Perform any synchronous or asynchronous operation here.
        await writer.writeAsync(chunk);
    }
}

run();

Augment Stream API

Use addAsyncFunctions to add the reader and/or writer functions to a stream object.

const fs = require('fs');
const aw = require('awaitify-stream');
const lineLength = 6; // 5 + the newline character.

function delay(ms) {
    return new Promise((resolve) => {
        setTimeout(resolve, ms);
    });
}

async function run() {
    let readStream = aw.addAsyncFunctions(fs.createReadStream('zipCodes.txt'));
    readStream.setEncoding('utf8');

    // print zip codes, slowly.
    let zipCode;
    while (null !== (zipCode = await readStream.readAsync(lineLength))) {
        // Remove the newline character. If you didn't set the encoding
        // above, use zipCode.toString().trim()
        zipCode = zipCode.trim();

        console.log(zipCode);
        await delay(200);
    }
}

run();