Content-Type does not respect optional charset encoding for iOS RCTJavascriptLoader

[justinr1234]

Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

1. react-native -v: 0.42.0
2. node -v: v6.11.2
3. npm -v: 4.6.1
4. yarn --version: 0.27.5

• Target Platform: iOS
• Development Operating System: macOS
• Build tools: XCode

Steps to Reproduce

1. Try to run a react native app and download a bundle from a server which returns a Content-Type header that includes both the MIME Type and an optional character encoding as specified here: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type
2. The React Native code for iOS will fail on this line of code as it strictly checks the Content-Type header as if the optional character encoding doesn't exist: https://github.com/facebook/react-native/blame/master/React/Base/RCTJavaScriptLoader.mm#L277

Expected Behavior

The code should follow the specification of Content-Type and respect only MIMEType checking instead of strictly checking the Content-Type header for an exact match on MIMEType.

Per Apple documentation, NSURLResponse contains the MIMEType field that should be checked for application/javascript instead of checking the raw Content-Type header: https://developer.apple.com/documentation/foundation/nsurlresponse

Actual Behavior

Though this was encountered while using Expo, the error is nonetheless coming from the RCTJavaScriptLoader

Expected JavaScript, but got content type 'application/javascript; chartset=UTF-8'. Check that your internet connection is working.

Reproducible Demo

https://github.com/sysgears/apollo-universal-starter-kit

Follow starter instructions and checkout this commit: sysgears/apollo-universal-starter-kit@bbcd52a

The problem is worked around after this commit in the project.

[joearasin]

I just tripped over this when attempting to get Haul to make a build for react-native 0.48.2: callstack/haul#228

[anp]

cc'ing @janicduplessis as he was cc'd on an Expo bug report.

[grabbou]

Up @janicduplessis, there are some commits in the history of this issue. Is any of them ready for merging? If yes, I can go ahead and cherry-pick into respective branches.

[janicduplessis]

The PR has not been merged yet #15792, let's cherry pick it once it is.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. If you think this issue should definitely remain open, please let us know why. Thank you for your contributions.

[justinr1234]

@janicduplessis did this end up getting merged somewhere?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. If you think this issue should definitely remain open, please let us know why. Thank you for your contributions.