Only avalible solution what I find it is using backgrounf.html, wich load firebase.js (<script> tag) and with messaging betwin background and conten scripts.

But if u know how download firebase.js or how transform firebase.js in order to use the js file in chrome extension - please tell me

Same problem...

Seeing the same thing...

same problem

I found a work-around. It doesn't look pretty, but by recompiling the second library that is included in firebase.js with Google closure compiler I was able to make it work: https://pastebin.com/QPDqVimD

Another workaround by avoiding to import firebase-auth.js https://stackoverflow.com/a/49496631/1121123. The issue is likely the same as pouchdb/pouchdb#5798 due to the minifier (and settings) used

@davemart-in your solution's awesome ! it solves it perfectly! Thanks!

I think leaving firebase-auth.js out is the best solution. You can auth in the chrome background or in the frame that pops up when you click on the icon. You can use send message to pass the auth token somehow.

@davemart-in Brilliant! it solves it perfectly! Thank You!

So I don't know what this approach might break.. but I wasn't happy with recompiling or using background.html and sending messages. So I searched the source for \u and eventually you come across the character � it is used in this snippet of code xb=/\uffff/.test("�"). If you remove all instances of this character so that the code reads xb=/\uffff/.test("") then the error no longer appears but everything seems to work as normal (database and auth at least).

FWIW, my guess is that line is coming from auth's use of closure's json library... https://github.com/google/closure-library/blob/db35cf1524b36a50d021fb6cf47271687cc2ea33/closure/goog/json/json.js#L305

Not 100% sure why it triggers the UTF-8 error or if there's a workaround though.

Yes, I believe this is the check (unminified) that I referenced in the comment above. Reassuring to see that it probably won't have any adverse effects on other browsers. Although my removal of the .test('\uffff') for test('') means that the ternary always take the first branch.

Also, for the record, I never actually managed to auth from the content script in the end, there is no was to access chrome.identity.getAuthToken from a content script and that is how all the examples suggest it should be done.

I have the same problem with PHP when I extract text from HTML string by substr function.
substr($meta, 0, 160);
Look everything is good with echo but when use print_r function, end of extracted string has a mark like this ��.

The solution for who has the same problem like me:
mb_substr($meta, 0, 160, "utf-8")

Is recompiling still the best solution for this? I attempted to recompile firebase.js and the complier threw an error. I was able to recompile individual libs i.e auth, app, firestone. however I get the same error after replacing my node_modules code with the recompiled code