On Webpack and CRA build there is an WARN "Critical dependency: the request of a dependency is an expression"

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You want to:

• report a sort of bug
• request a feature

Current behaviour

When the webpack is trying to put the engine.io in a bundle, we get an optimization warning due to an expression in require() of the engine.io library.

Webpack tries to resolve required calls statically to make a minimal bundle. Your library in node_modules/engine.io/lib/server.js file and at line 80 it doing this:

this.opts.wsEngine === "ws" ? require("ws") : require(this.opts.wsEngine);

The last require() has an expression as argument.

Can we rid of this warn?

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

• Add the engine.io into a project with a webpack builder.
• Build the app to make a bundle that has the engine.io.

Expected behaviour

• No Webpack warning: “Critical dependency: the request of a dependency is an expression”

Setup

• OS: macOs
• browser: node v12.19
• engine.io version: 4.0.1

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

The warning:

WARNING in ./node_modules/engine.io/lib/server.js 74:67-94
Critical dependency: the request of a dependency is an expression
 @ ./node_modules/engine.io/lib/engine.io.js
 @ ... the node app ...

[darrachequesne]

That makes sense 👍 let’s schedule this for v5 then.

[darrachequesne]

Fixed by https://github.com/socketio/engine.io/commit/edb734316f143bf0f1bbc344e966d18e2676b934 and included in engine.io@5.0.0.