Stream Is Readable

Introduction

In this lab, we will explore how to check if a given argument is a readable stream in JavaScript. We will learn how to use the typeof operator to check the type of the argument and how to access the _read and _readableState properties of a stream. By the end of this lab, you will have a better understanding of how to work with streams in JavaScript.

Check if a Stream is Readable

To check if a given argument is a readable stream, follow these steps:

• First, open the Terminal/SSH and type node to start practicing coding.
• Check if the value is not null.
• Use typeof to check if the value is an object and the pipe property is a function.
• Additionally, check if the typeof the _read and _readableState properties are function and object, respectively.

Here's an example function that implements these steps:

const isReadableStream = (val) =>
  val !== null &&
  typeof val === "object" &&
  typeof val.pipe === "function" &&
  typeof val._read === "function" &&
  typeof val._readableState === "object";

You can use this function to check if a stream is readable, like this:

const fs = require("fs");

isReadableStream(fs.createReadStream("test.txt")); // true

Summary

Congratulations! You have completed the Stream Is Readable lab. You can practice more labs in LabEx to improve your skills.