Introduction to `is-stream`

The `is-stream` module is an invaluable tool in the realm of Node.js for determining object types, particularly streams. This lightweight module provides developers with a seamless way to identify streams and handle various stream types effectively.

API Examples

1. Installation

    npm install is-stream

2. Basic Usage

Here is how you can use the `is-stream` module to check if an object is a stream:

    const isStream = require('is-stream');
    const stream = require('stream');

    console.log(isStream(new stream.Readable())); // true
    console.log(isStream({})); // false

3. Checking Different Stream Types

isStream.readable

    console.log(isStream.readable(new stream.Readable())); // true
    console.log(isStream.readable(new stream.Writable())); // false

isStream.writable

    console.log(isStream.writable(new stream.Writable())); // true
    console.log(isStream.writable(new stream.Duplex())); // true

isStream.duplex

    console.log(isStream.duplex(new stream.Duplex())); // true
    console.log(isStream.duplex(new stream.Transform())); // true

isStream.transform

    console.log(isStream.transform(new stream.Transform())); // true

4. Real-World Application Example

Suppose you are building a file processing application. You can use `is-stream` to check the type of stream and proceed accordingly:

    const fs = require('fs');
    const isStream = require('is-stream');
    const stream = require('stream');

    const readStream = fs.createReadStream('source.txt');
    const writeStream = fs.createWriteStream('destination.txt');

    if (isStream(readStream) && isStream.writable(writeStream)) {
      readStream.pipe(writeStream);
    } else {
      console.error('Error: One of the provided streams is not valid.');
    }

This simple application reads a file (‘source.txt’) and writes its content to another file (‘destination.txt’). The `is-stream` module ensures that both the read and write streams are valid before proceeding.

In summary, `is-stream` is a powerful utility that can significantly enhance your Node.js application’s resilience by accurately identifying different types of streams.

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