HttpClient POST using request() method error on Firefox: event is not defined

[SpeedoPasanen]

I'm submitting a...

[ x ] Bug report 

Current behavior

In Firefox, trying to upload FormData using HttpClient.request() instead of .post() causes event is not defined. I just moved to using .request() because I want to track the upload progress, and everything was working previously.

The error occurs before request is sent, ie. nothing in the network tab.

Expected behavior

Should work as it does in Chrome, Edge and IE11.

Minimal reproduction of the problem with instructions

Open this StackBlitz in Firefox, select a file with the input, see error in console.

On Chrome, you should see 403 as expected. On FF, you should see event is undefined and a stack trace pointing to a weird line number in common/esm5/http.js.

Hacked a bit into http.js and added logging to both places where I could find the name event, which is in onUpProgress() and onDownProgress() and neither one of these gets ever called on FF, so I can't figure out where this event even is.

Environment

Angular version: 5.2.8

Browser:
- [ ] Chrome (desktop) version XX
- [ ] Chrome (Android) version XX
- [ ] Chrome (iOS) version XX
- [ x ] Firefox version 58.0.2
- [ ] Safari (desktop) version XX
- [ ] Safari (iOS) version XX
- [ ] IE version XX
- [ ] Edge version XX
 
- Platform:  Windows

Other

StackOverflow question

[SpeedoPasanen]

Made a simplified blitz (original link updated as well) to rule out as much as possible. Now posting a File instead of FormData like in the guide example. Result was the same:
https://stackblitz.com/edit/angular-7bagc2?file=app/app.component.ts

[SpeedoPasanen]

Ehh hmm.. the problem was I return event in the map call, instead of e. There is no event. Weird that the compiler and other browsers let that slip, and what a wonderfully useful stack trace FireFox! Sorry about this! Closing. Working blitz: https://stackblitz.com/edit/angular-rptitf?file=app/app.component.ts

[trotyl]

For tracking: microsoft/TypeScript#18433

[SpeedoPasanen]

Oh, event is declared in lib.dom.d.ts. Very enlightening read, thanks @trotyl !

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