npm run build fails for EventEmitter

[godmar]

@gaearon asked that I file a separate issue.

How to reproduce: run create-react-app fail-event-emitter, add a line

import EventEmitter from 'events';

to src/index.js and then run npm run build, which fails with:

> fail-event-emitter@0.1.0 build /home/gback/fail-event-emitter
> react-scripts build

Creating an optimized production build...
Failed to compile.

static/js/main.068c41be.js from UglifyJs
Unexpected character '`' [/usr/lib/nodejs/events.js:260,0]

react-scripts 0.7.0 is used and node.js 6.9.1 (or 7.0)

The purported cause is that CRA does not transpile "dependencies" into ES5 and then the UglifyJS plugin fails when it encounters ES6 code.
The test case above was derived from a failure in react-bootstrap-tables, which includes a module that in turn references EventEmitter. Others have suggested to provide an alternate EventEmitter implementation in the application path, but it is not clear to me how react-bootstrap-table's dependencies can be made to use this alternate implementation.

[godmar]

Same issue when including "recharts": "^0.18.0". This package also includes EventEmitter.

It looks as though at this point, the chances of successfully building a 'production' build with create-react-app are rather low.

In related posts, it was mentioned as a work-around to include our own implementation of EventEmitter. Can someone describe how to do that? Specifically, I do not know how to ensure that dependencies such as recharts import the included implementation of EventEmitter rather than falling back onto node.js's. Is there a webpack setting? If so, react-scripts should probably include it.

Would be great if this were addressed. Currently the only work-around is to disable the 'UglifyJSPlugin', but this requires reaching inside CRA (or ejecting).

[henri-hulski]

We replaced the node EventEmitter with EventEmitter3 for Cerebral2.

But this was only possible because we are the authors of all dependencies which use the EventEmitter.

[gaearon]

Can you investigate where this problem is coming from? I'm sorry I don't have much time to investigate it right now but I'd be happy to accept a fix for it.

It looks as though at this point, the chances of successfully building a 'production' build with create-react-app are rather low.

Well this problem never occurred before, so it must be something new. Can you take time to figure out why it happens and propose a fix?

[gaearon]

In particular I would expect Webpack to take EventEmitter implementation from some collection of shims. The question is, then, why those shims aren't in ES5 anymore and where they are located. This is not something you would require CRA maintainers to investigate—you could try to dig into it by yourself and figure out which package is responsible for that code and when it changed.

[thien-do]

Updated: comment deleted since I'm misunderstand the situation 😄

[jquense]

generally the webpack shims come from: https://github.com/webpack/node-libs-browser assuming something else isn't messing with the module resolution

[gaearon]

The question is, then, what changed there that the source of EventEmitter is no longer ES5.

[henri-hulski]

events.js uses template strings from node 6.0.0.
They were introduced in c6656db.

[henri-hulski]

So it comes from core node.
But not happens on all machines so not really sure why.

[thien-do]

@henri-hulski it seems webpack is supposed to not use that native implementation from NodeJS, but instead use one from node-libs-browser.