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module ws does not provide an export named WebSocketServer

· One min read
John Reilly
John Reilly
OSS Engineer - TypeScript, Azure, React, Node.js, .NET

I use Playwright for testing and mock Web Socket calls with the ws package. I recently did an npm upgrade and found myself hitting this error message when I tried to run tests:

SyntaxError: The requested module 'ws' does not provide an export named 'WebSocketServer'

It was caused by the following code:

import { WebSocketServer } from 'ws'; // this goes bang!

// ...

const mockWsServer = new WebSocketServer({ port: 5000 });

The fix was surprisingly simple to implement but hard to search for. That's why I'm writing this.

Resolving "The requested module 'ws' does not provide"...​

This fix is as simple switching the code to:

import ws from 'ws';

// ...

const mockWsServer = new ws.Server({ port: 5000 });

And that should resolve the issue.