Cannot use debug with Rollup

There’re a troubles both using debug directly (via import debug from 'debug') and as a dependency to another package, with Rollup bundler.

1. import debug from 'debug':

Non-existent export ‘default’ is imported from node_modules/debug/src/browser.js

I believe this is because of that dynamic stuff.

1. import SocketIo from 'socket.io-client' which has debug as a dependency:

‘default’ is not exported by ‘node_modules/socket.io-client/node_modules/debug/src/browser.js’

As far as I understood, the main idea behind browser.js is to import kinda «base» debug object and upgrade it with browser-specific methods’ implementations. I believe this can be rewritten in more static and bundler-friendly way. Like requiring base, propagate it with methods and then export as a default in different statements which would simplify the analysis by Rollup and other-like.

I’m not an active debug user, but debug is very popular tool, so many of my packages’ of choice using it as a dependency. So I stumble upon it when bundling, from time to time. Leveraging any workarounds is diffcult, since I do not have precision control over dependencies of my dependencies.

[Rich-Harris]

@StreetStrider that’s a fair assessment of what’s happening. But it sounds like this is probably a fixable bug in rollup-plugin-commonjs — I suspect it just doesn’t know what to make of this code:

exports = module.exports = require('./debug');

I’ve opened a related issue over there: https://github.com/rollup/rollup-plugin-commonjs/issues/204

[iFwu]

If I don’t use dist version of debug, the arrow functions in src/browser will not run in IE11.

That’s not a problem with Rollup. You need to use Babel.

You can tell that I need to transpile, but when I use babel with typescript and it will cause this issue when compiled to common-js plugin of rollup.

This doesn’t make any sense. Can you explain, please?

After separating the node and browser build, the problem no longer exists.