Symbol should not be polyfilled on Chrome 49 (neither on Chrome 42 and 38)

[Nickinthebox]

On Chrome 49 (windows XP), we have an error: TypeError: Cannot redefine property: replace if our polyfill.io URL include the polyfill of Symbol.

Chrome 49 is the last available Chrome on Windows XP / Vista and Mac OS 10.6-10.8 (x64)
Chrome 42 is the last available Chrome on Android 4
Chrome 38 is the last available Chrome on Mac OS 10.6 (I1-32)

I checked on https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol and fixed some limits in the code for Symbol as well as Symbol.iterator and Symbol.unscopables.

However, according to https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/replace , Symbol.replace (which seems to cause the error) is only supported from version 50... so I have let <50 for the Symbol.replace config... I hope the error will disappear with this PR (not tested).

[CLAassistant]

All committers have signed the CLA.

[JakeChampion]

Hi @Nickinthebox - thanks for the pull-request, the tests for this are running at https://github.com/Financial-Times/polyfill-library/actions/runs/1875430851

[JakeChampion]

@Nickinthebox have you ran the tests for this polyfill on chrome 38 and seen that they pass? The same question applies to the other polyfills in the pull-request as well.

If not, I can do that sometime this week 👍

[JakeChampion]

@Nickinthebox The tests for Chrome 42 and lower are failing on this pull-request - https://github.com/Financial-Times/polyfill-library/runs/5272168306?check_suite_focus=true

Would you be able to look into resolving those at all?

[Nickinthebox]

This is weird because the fail of tests are on other polyfill.

For example, in the logs I see:

2022-02-21T10:13:11.5367221Z Failures:�[39m�[22m
2022-02-21T10:13:11.5370279Z  - chrome/38.0:
2022-02-21T10:13:11.5370939Z     -> AbortController passes the feature detect
2022-02-21T10:13:11.5372056Z        http://bs-local.com:9876/test?includePolyfills=yes&always=no&feature=AbortController
2022-02-21T10:13:11.5372596Z        false == true
2022-02-21T10:13:11.5372994Z  - chrome/38.0:
2022-02-21T10:13:11.5373508Z     -> AbortController AbortSignal is a function
2022-02-21T10:13:11.5374228Z        http://bs-local.com:9876/test?includePolyfills=yes&always=no&feature=AbortController
2022-02-21T10:13:11.5374746Z        AbortSignal is not defined

Which is about AbordSignal which is supposed to be polyfilled on Chrome 38:
https://github.com/Financial-Times/polyfill-library/blob/master/polyfills/AbortController/config.toml

And this is not changed by my PR... 🤷

[JakeChampion]

This is weird because the fail of tests are on other polyfill.

For example, in the logs I see:

2022-02-21T10:13:11.5367221Z Failures:�[39m�[22m
2022-02-21T10:13:11.5370279Z  - chrome/38.0:
2022-02-21T10:13:11.5370939Z     -> AbortController passes the feature detect
2022-02-21T10:13:11.5372056Z        http://bs-local.com:9876/test?includePolyfills=yes&always=no&feature=AbortController
2022-02-21T10:13:11.5372596Z        false == true
2022-02-21T10:13:11.5372994Z  - chrome/38.0:
2022-02-21T10:13:11.5373508Z     -> AbortController AbortSignal is a function
2022-02-21T10:13:11.5374228Z        http://bs-local.com:9876/test?includePolyfills=yes&always=no&feature=AbortController
2022-02-21T10:13:11.5374746Z        AbortSignal is not defined

Which is about AbordSignal which is supposed to be polyfilled on Chrome 38: https://github.com/Financial-Times/polyfill-library/blob/master/polyfills/AbortController/config.toml

And this is not changed by my PR... 🤷

This is likely because AbortSignal depends on Symbol, which was changed in this pull-request

[JakeChampion]

/ok-to-test sha=e0be16b

running tests at https://github.com/Financial-Times/polyfill-library/actions/runs/4902362724

[romainmenke]

@Nickinthebox I've tried to reproduce the issue you are facing but I wasn't able to.
From your comment I understand that the issue is happening only in Chrome 49?

If you are using polyfill.io you shouldn't be getting the Symbol polyfill in Chrome 49.
Lowering the version constraints further won't change much.

In chrome 49 :

https://polyfill.io/v3/polyfill.min.js?features=Symbol.replace
-> only Symbol.replace

https://polyfill.io/v3/polyfill.min.js?features=Symbol
-> no polyfills

---

Is it possible your project is also using core-js and is effectively having two polyfills for Symbol.replace? One from core-js and one from polyfill.io

[Nickinthebox]

In deed we also use core-js! I will dig into this. Sorry for the noise.

[JakeChampion]

In deed we also use core-js! I will dig into this. Sorry for the noise.

@Nickinthebox and/or @romainmenke should we be closing this PR?

[mhassan1]

Closed as not needed