nodejs: Check if variable is readable stream
node.js
Solution
Your problem is definitely that you haven't required `stream`. But. `instanceof` is not a good method to check if variable is a readable stream. Consider following cases:
- object can be old-style stream (instance of `stream.Stream`);
- object can be just emitter with `data` and `end` events;
- object can be instance of `Readable` from external module (https://github.com/isaacs/readable-stream);
The best way to go is duck typing. Basically, if you are going to `pipe` stream, check if it has `pipe` method, if you are going to listen to events, check if stream has `on` method, etc.
Problem
How i can check if a var is a readable stream in Nodejs? Example: ``` function foo(streamobj){ if(streamobj != readablestream){ // Error: no writable stream }else{ // So something with streamobj } } ``` I tried ``` if (!(streamobj instanceof stream.Readable)){ ``` But than i get a ReferenceError: stream is not defined