Introduction to is-stream

The is-stream module is an incredibly useful utility for Node.js developers to determine whether a given object is a stream. Streams are essential components in Node.js, enabling efficient reading, writing, and piping of data. This guide covers the extensive API of is-stream with practical examples to help you integrate it seamlessly into your applications.

API Overview

isStream(value)

Checks if value is a stream.

  
  const isStream = require('is-stream');
  
  console.log(isStream(fs.createReadStream('example.txt'))); // true
  

isStream.writable(value)

Checks if value is a writable stream.

  
  const {Writable} = require('stream');
  const isStream = require('is-stream');
  
  const writableStream = new Writable({
    write(chunk, encoding, callback) {
      callback();
    }
  });
  
  console.log(isStream.writable(writableStream)); // true
  

isStream.readable(value)

Checks if value is a readable stream.

  
  const {Readable} = require('stream');
  const isStream = require('is-stream');
  
  const readableStream = new Readable({
    read(size) {
      this.push('data');
    }
  });
  
  console.log(isStream.readable(readableStream)); // true
  

isStream.duplex(value)

Checks if value is a duplex stream.

  
  const {Duplex} = require('stream');
  const isStream = require('is-stream');
  
  const duplexStream = new Duplex({
    read(size) {
      this.push('data');
    },
    write(chunk, encoding, callback) {
      callback();
    }
  });
  
  console.log(isStream.duplex(duplexStream)); // true
  

isStream.transform(value)

Checks if value is a transform stream.

  
  const {Transform} = require('stream');
  const isStream = require('is-stream');
  
  const transformStream = new Transform({
    transform(chunk, encoding, callback) {
      callback(null, chunk.toString().toUpperCase());
    }
  });
  
  console.log(isStream.transform(transformStream)); // true
  

Example Application

Below is an example of using the is-stream module to validate streams in a small Node.js application:

  
  const fs = require('fs');
  const {Readable, Writable} = require('stream');
  const isStream = require('is-stream');

  const readableStream = fs.createReadStream('input.txt');
  const writableStream = fs.createWriteStream('output.txt');

  if (isStream.readable(readableStream) && isStream.writable(writableStream)) {
    readableStream.pipe(writableStream);
    console.log('Piping stream from input.txt to output.txt');
  } else {
    console.log('Invalid stream');
  }
  

With is-stream, verifying stream types becomes straightforward, making it easier to manage stream operations within your applications. Integrate this module to enhance the robustness of your stream handling logic.

Hash: 73d56d960864c3d853381391b43ba491d658a719f03ba10c61c5685acc5511cd