A promise based asynchronous stream reader, which makes reading from a stream easy.
Allows to read and peek from a Readable Stream
Note that peek-readable was formally released as then-read-stream.
npm install --save peek-readable
The peek-readable
contains one class: StreamReader
, which reads from a stream.Readable.
Module: version 5 migrated from CommonJS to pure ECMAScript Module (ESM). JavaScript is compliant with ECMAScript 2019 (ES10). Requires Node.js โฅ 14.16 engine.
In the following example we read the first 16 bytes from a stream and store them in our buffer. Source code of examples can be found here.
import fs from 'node:fs';
import { StreamReader } from 'peek-readable';
(async () => {
const readable = fs.createReadStream('JPEG_example_JPG_RIP_001.jpg');
const streamReader = new StreamReader(readable);
const uint8Array = new Uint8Array(16);
const bytesRead = await streamReader.read(uint8Array, 0, 16);;
// buffer contains 16 bytes, if the end-of-stream has not been reached
})();
End-of-stream detection:
(async () => {
const fileReadStream = fs.createReadStream('JPEG_example_JPG_RIP_001.jpg');
const streamReader = new StreamReader(fileReadStream);
const buffer = Buffer.alloc(16); // or use: new Uint8Array(16);
try {
await streamReader.read(buffer, 0, 16);
// buffer contains 16 bytes, if the end-of-stream has not been reached
} catch(error) {
if (error instanceof EndOfStreamError) {
console.log('End-of-stream reached');
}
}
})();
With peek you can read ahead:
import fs from 'node:fs';
import { StreamReader } from 'peek-readable';
const fileReadStream = fs.createReadStream('JPEG_example_JPG_RIP_001.jpg');
const streamReader = new StreamReader(fileReadStream);
const buffer = Buffer.alloc(20);
(async () => {
let bytesRead = await streamReader.peek(buffer, 0, 3);
if (bytesRead === 3 && buffer[0] === 0xFF && buffer[1] === 0xD8 && buffer[2] === 0xFF) {
console.log('This is a JPEG file');
} else {
throw Error('Expected a JPEG file');
}
bytesRead = await streamReader.read(buffer, 0, 20); // Read JPEG header
if (bytesRead === 20) {
console.log('Got the JPEG header');
} else {
throw Error('Failed to read JPEG header');
}
})();