Avoid using `debug` module and other node builtins in client library

Note: for support questions, please use one of these channels: stackoverflow or slack

You want to:

• report a bug
• request a feature

Current behaviour

Use socket-io.client in an app and build it with rollup

JS file

const io = require('socket.io-client')
...

Build with rollup

5:44:40 PM watch.1  |  (!) Unresolved dependencies
5:44:40 PM watch.1  |  https://github.com/rollup/rollup/wiki/Troubleshooting#treating-module-as-external-dependency
5:44:40 PM watch.1  |  tty (imported by ../frappejs/node_modules/socket.io-client/node_modules/debug/src/node.js, commonjs-external:tty, ../frappejs/node_modules/socket.io-parser/node_modules/debug/src/node.js, ../frappejs/node_modules/debug/src/node.js)
5:44:40 PM watch.1  |  util (imported by ../frappejs/node_modules/socket.io-client/node_modules/debug/src/node.js, commonjs-external:util, ../frappejs/node_modules/socket.io-parser/node_modules/debug/src/node.js, ../frappejs/node_modules/debug/src/node.js)
5:44:40 PM watch.1  |  fs (imported by ../frappejs/node_modules/socket.io-client/node_modules/debug/src/node.js, commonjs-external:fs, ../frappejs/node_modules/socket.io-parser/node_modules/debug/src/node.js, ../frappejs/node_modules/xmlhttprequest-ssl/lib/XMLHttpRequest.js, ../frappejs/node_modules/bindings/bindings.js)
5:44:40 PM watch.1  |  net (imported by ../frappejs/node_modules/socket.io-client/node_modules/debug/src/node.js, commonjs-external:net, ../frappejs/node_modules/socket.io-parser/node_modules/debug/src/node.js)
5:44:40 PM watch.1  |  url (imported by ../frappejs/node_modules/xmlhttprequest-ssl/lib/XMLHttpRequest.js, commonjs-external:url, ../frappejs/node_modules/ws/lib/WebSocket.js, ../frappejs/node_modules/ws/lib/WebSocketServer.js)
5:44:40 PM watch.1  |  child_process (imported by ../frappejs/node_modules/xmlhttprequest-ssl/lib/XMLHttpRequest.js, commonjs-external:child_process)
5:44:40 PM watch.1  |  http (imported by ../frappejs/node_modules/xmlhttprequest-ssl/lib/XMLHttpRequest.js, commonjs-external:http, ../frappejs/node_modules/ws/lib/WebSocket.js, ../frappejs/node_modules/ws/lib/WebSocketServer.js)
5:44:40 PM watch.1  |  https (imported by ../frappejs/node_modules/xmlhttprequest-ssl/lib/XMLHttpRequest.js, commonjs-external:https, ../frappejs/node_modules/ws/lib/WebSocket.js)
5:44:40 PM watch.1  |  events (imported by ../frappejs/node_modules/ws/lib/WebSocket.js, commonjs-external:events, ../frappejs/node_modules/ws/lib/WebSocketServer.js)
5:44:40 PM watch.1  |  crypto (imported by ../frappejs/node_modules/ws/lib/WebSocket.js, ../frappejs/node_modules/ws/lib/Sender.js, commonjs-external:crypto, ../frappejs/node_modules/ws/lib/WebSocketServer.js)
5:44:40 PM watch.1  |  buffer (imported by ../frappejs/node_modules/safe-buffer/index.js, commonjs-external:buffer)
5:44:40 PM watch.1  |  zlib (imported by ../frappejs/node_modules/ws/lib/PerMessageDeflate.js, commonjs-external:zlib)
5:44:40 PM watch.1  |  path (imported by ../frappejs/node_modules/bindings/bindings.js, commonjs-external:path)
5:44:40 PM watch.1  |  (!) Missing global variable names
5:44:40 PM watch.1  |  Use output.globals to specify browser global variable names corresponding to external modules
5:44:40 PM watch.1  |  tty (guessing 'tty')
5:44:40 PM watch.1  |  util (guessing 'util')
5:44:40 PM watch.1  |  fs (guessing 'fs')
5:44:40 PM watch.1  |  net (guessing 'net')
5:44:40 PM watch.1  |  url (guessing 'url')
5:44:40 PM watch.1  |  child_process (guessing 'child_process')
5:44:40 PM watch.1  |  http (guessing 'http')
5:44:40 PM watch.1  |  https (guessing 'https')
5:44:40 PM watch.1  |  buffer (guessing 'buffer')
5:44:40 PM watch.1  |  path (guessing 'path')
5:44:40 PM watch.1  |  zlib (guessing 'zlib')
5:44:40 PM watch.1  |  crypto (guessing 'crypto')
5:44:40 PM watch.1  |  events (guessing 'events')

Steps to reproduce (if the current behaviour is a bug)

See above

Expected behaviour

Should be include client library easily without nodejs builtins

Setup

• OS:
• browser:
• socket.io version: 2.0.4

Other information (e.g. stacktraces, related issues, suggestions how to fix)

Client libraries should be dependent only on browser API.

Using nodejs builtins (debug) creates “dependency hell”. I had to include socket.io-client separately with the <script> tag finally.

[Akatuoro]

For anyone still running into this issue (like me today), make sure to use the option browser: true for @rollup/plugin-node-resolve.

Excluding the debug module like in the slim webpack build mentioned above does still reduce the bundle size.

[darrachequesne]

Added in the documentation here: https://socket.io/docs/v4/client-with-bundlers/#browser-1