How to serve output of flutter build web --wasm.

[ebala96]

Steps to reproduce

I am taking a wasm build of my application by running flutter build web --wasm and trying to serve this using my dart server.
Since this creates dual-compatible output for both dart2js and wasm, it picks the js bundle by default.

I also tried the following config in my index.html file.
config : {"compileTarget":"dart2wasm","renderer":"skwasm","mainWasmPath":"main.dart.wasm","jsSupportRuntimePath":"main.dart.mjs"} inside _flutter.loader.load

This throws an error FlutterLoader could not find a build compatible with configuration and environment.

Actual results

Looking for a way to set the config to pick wasm file when I serve the output of flutter build web --wasm.

Flutter Doctor output

Doctor output

[✓] Flutter (Channel stable, 3.24.4, on Ubuntu 22.04.5 LTS 5.15.0-117-generic, locale en_US.UTF-8)
    • Flutter version 3.24.4 on channel stable at /usr/local/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 603104015d (3 weeks ago), 2024-10-24 08:01:25 -0700
    • Engine revision db49896cf2
    • Dart version 3.5.4
    • DevTools version 2.37.3

[✗] Android toolchain - develop for Android devices
    ✗ Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/to/linux-android-setup for detailed instructions).
      If the Android SDK has been installed to a custom location, please use
      `flutter config --android-sdk` to update to that location.


[✓] Chrome - develop for the web
    • CHROME_EXECUTABLE = /chrome

[✓] Linux toolchain - develop for Linux desktop
    • Ubuntu clang version 14.0.0-1ubuntu1.1
    • cmake version 3.22.1
    • ninja version 1.10.1
    • pkg-config version 0.29.2

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/to/linux-android-setup for detailed instructions).

[✓] Connected device (2 available)
    • Linux (desktop) • linux  • linux-x64      • Ubuntu 22.04.5 LTS 5.15.0-117-generic
    • Chrome (web)    • chrome • web-javascript • Chromium 122.0.6177.0

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 2 categories.

[huycozy]

Hi @ebala96
How do you serve your web? Please check this to see if it helps: https://docs.flutter.dev/platform-integration/web/wasm#serve-the-built-output-with-an-http-server

Please also check #154541 if it's similar to your case.

[github-actions]

Without additional information, we are unfortunately not sure how to resolve this issue. We are therefore reluctantly going to close this bug for now.
If you find this problem please file a new issue with the same description, what happens, logs and the output of 'flutter doctor -v'. All system setups can be slightly different so it's always better to open new issues and reference the related ones.
Thanks for your contribution.

[Levi-Lesches]

@huycozy, that section of the docs has since been removed in flutter/website#11367

@sfshaza2, that section was marked as "not needed" since Flutter run works by default, but that doesn't address the issue of serving a release build from your own web server. This page of Chrome Developers seems to suggest the config is still very much needed.

Can we consider re-adding it?

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.