How to check if a value/argument/resource is a writable stream in node

Question

I would like to know how to check if a value/argument/resource in node.js is a writable stream.

Is there a function or method to do that?

Thanks

Answer 1

You can just check

// include node stream module
const stream = require('stream');

// check if stream is an instance of a Writable Stream
let isWritableStream = yourStream instanceof stream.Writable

Note: in your program, your customized "Writable Stream Classes" should extends the stream.Writable class. In order to extends it you may check How to implement a writable stream (Stack Overflow)

References:

1. stream.Writable (Node.js v.0.9.4+)
2. instanceof (MDN)