Dynamic Import Hangs

[dsanders11]

@jdalton, sorry if I'm missing something obvious here, trying to get something working for a deadline so can't deep dive.

I can't seem to get import() to do anything in Electron. I have a reproduce case here, but I'll reproduce the code here since it's simple:

import('./foo.js').then(module => {
  console.log('success', module)
}).catch(error => {
  console.error('error', error)
})

I'd expect that to either resolve or reject, but instead neither happens. I've tried a number of different things with no change:

• File suffix of .mjs
• Configuring esm to "module": "all"
• Various combinations of import('foo.js'), import('./foo'), etc

Any pointer in the right direction?

P.S. Can installed package names be used, like import('events')?

[jdalton]

Hi @dsanders11!

I can't speak to the failure of promise resolve or reject (I'll need to dig in more), but I can tell you what the issue is outside of that. If you're using .mjs then no esm options apply to it. This means "mode": "all" will not be respected by .mjs files and it will treat .js files as CJS with only a default export. If you're looking for ecosystem interop/support you should use .js instead of .mjs.

[dsanders11]

Good to know, but .mjs was just one of the various combination I tried to see if I could make the needle move at all.

For the moment I've fallen back to using require() to get a similar effect (but synchronous instead of aync).

[jdalton]

Have you tried Electron 3 stable?

[dsanders11]

@jdalton, yes, I just tried changing that branch to Electron 3 stable, same result.

[jdalton]

Thanks for the repro. I narrowed it down to something funky with builtin setImmediate. It looks like something is going wrong in their wrapper:

https://github.com/electron/electron/blob/539d6d20b73a29e363489f4b528eddf22a2a2e47/lib/common/init.js#L33-L34

Update:

It's because I'm using require('timers').setImmediate and Electron wraps window.setImmediate. So I'm missing out on their special wrap.

Update:

Patched b85f671. To see logs in the renderer process you'll want to mainWindow.webContents.openDevTools() from main.js.

[dsanders11]

@jdalton, thanks for the quick fix! I've confirmed in the repro case that it's now acting as expected.