Application breaks on IE11 with Ember.js 3.6

[YoranBrondsema]

Yesterday we upgraded our app to Ember.js 3.6 but noticed that that broke it on IE11. We've had IE11 set as a target in config/targets.js this whole time.

It breaks on the first define in app.js, i.e. the bundle containing all the application-specific Javascript. The error is:

'define' is undefined

I see that PRs #17188 and #17246 might have something to do with it. I checked the value of needsLegacyBuild from https://github.com/emberjs/ember.js/blob/v3.6.1/lib/index.js#L84 during the build and it's set to true, as you would expect. So I'm not too sure about where the bug is.

[rwjblue]

Hmm, define is undefined seems like it would not be the first error, can you share any other errors triggered before that one? A minimal reproduction would also be very helpful...

[YoranBrondsema]

That's the first error I saw, I think. I reverted back to 3.5 now so can't check right away, but I'll work on a reproduction app tomorrow and get back to you.

[rwjblue]

Awesome, thank you!

[YoranBrondsema]

OK I figured it out. In the end it was my own fault, because I was importing the template compiler with

app.import('node_modules/ember-source/dist/ember-template-compiler.js');

instead of

app.import('vendor/ember/ember-template-compiler.js');

How come it didn't do the transpilation when importing directly from node_modules? I'm not too familiar with the internals.

Also, I figured it out through a StackOverflow answer. Since the template compiler is part of the core, maybe this is something that belongs in the guide? For instance on https://guides.emberjs.com/release/addons-and-dependencies/managing-dependencies/? I would be happy to open up a PR to document the proper way to import the template compiler somewhere in the docs.

[rwjblue]

Nothing is transpiled in node_modules, but the contents of vendor tree is either the "legacy" (IE11 compat node) or the "not ancient browser" build.

See #17402 for a similar issue and its fix in #17403.

[YoranBrondsema]

OK I see, thanks!