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samples/web_embedding/ng-flutter/README.md

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# ng-flutter
This Angular project is a simple example of how Angular and Flutter
web apps could be integrated, and have them interop.
## Points of Interest
### Angular
This repository is a quite standard Angular app. The following changes were made
to be able to use (and interop) with a Flutter web application:
* `package.json` has a custom `prebuild` script that builds the
Flutter web app, so Angular can find it later.
* `flutter.js` is added as a `"scripts"` entry in `angular.json`.
Angular takes care of minimizing and injecting it as any other script.
* The rest of the flutter app `flutter/build/web/` is registered
as an `"assets"` entry in `angular.json`, and moved to `/flutter`.
* The `ng-flutter` component takes care of embedding Flutter web, and yielding
control to Angular through an `appLoaded` `EventEmitter`. The object yielded
by this emitter is a state controller exposed by flutter via a JS custom
event!
### Flutter
The embedded Flutter application lives in the `flutter` directory of this repo.
That application is a standard web app, that doesn't need to be aware that it's
going to be embedded in another framework.
* Flutter uses new `@staticInterop` methods to allow certain Dart functions to
be called from JavaScript.
* Look at how `createDartExport` and `broadcastAppEvent` work together to make
the `_state` controller of the Flutter app available to Angular!
## How to build the app
### Requirements
If you want to build and run this demo on your machine, you'll need
a moderately recent version of Angular:
```console
$ ng version
Angular CLI: 16.0.1
Node: 18.16.0
Package Manager: npm 9.5.1
OS: linux x64
```
And Flutter:
```
$ flutter --version
Flutter 3.10.0-12.0.pre.38 • channel master
Framework • revision 1a51dc2131 (8 days ago) • 2023-04-24 12:25:21 -0700
Engine • revision 5fbde6c0fc
Tools • Dart 3.1.0 (build 3.1.0-35.0.dev) • DevTools 2.23.1
```
**Ensure `npm`, `ng` and `flutter` are present in your `$PATH`.**
### Building the app
This repository is a moderately standard Angular app. It integrates
Flutter web by making it part of the Angular `assets`.
In order to build this app, first fetch its `npm` dependencies:
```console
$ npm install
npm WARN deprecated @npmcli/move-file@2.0.1: This functionality has been moved to @npmcli/fs
added 963 packages, and audited 964 packages in 17s
93 packages are looking for funding
run `npm fund` for details
found 0 vulnerabilities
```
Then run the `build` script. It'll take care of building Flutter
automatically:
```console
$ npm run build
> ng-flutter@0.0.0 prebuild
... Flutter web build output ...
Compiling lib/main.dart for the Web...
> ng-flutter@0.0.0 build
> ng build
... Angular build output ...
✔ Browser application bundle generation complete.
✔ Copying assets complete.
✔ Index html generation complete.
```
### Local Angular development
Once you've reached this point, you should be able to work with
your Angular application normally, for example to run a local web
server:
```console
$ npm run start
> ng-flutter@0.0.0 start
> ng serve
✔ Browser application bundle generation complete.
Initial Chunk Files | Names | Raw Size
vendor.js | vendor | 4.38 MB |
... Angular build output...
** Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **
✔ Compiled successfully.
```
Navigate to `http://localhost:4200/`. The application will automatically reload if you change any of its Angular source files.
### Local Flutter web development
The Flutter app lives inside the `flutter` directory, and can be
developed independently. Just do any changes on Flutter web as you'd
normally do. It even includes a small `web/index.html` so you can see
changes to your app without running the whole Angular setup.
> **Note**
> For now, Angular does _not_ auto-detect changes to your Flutter web
app, so once you're happy with your Flutter web app, make sure to
call `npm run build` so everything rebuilds and gets placed into its
correct location.
### Deploying the app
After `npm run build`, you should have a deployable Angular + Flutter
web app in the `dist` directory of this Angular project.
Your built app can can be deployed anywhere, but do check
[Firebase hosting](https://firebase.google.com/docs/hosting) for a
super-easy deployment experience!
## Troubleshooting
### Flutter
Ensure your flutter app is properly rebuilt after any changes.
* Run `npm run build` to re-build the Flutter app.
If you encounter error messages like:
```
Error: Can't resolve 'flutter/build/web/flutter.js' in '/my/checkout/of/ng-flutter'
```
You definitely need to run `npm run build`!
## Reach out to the team(s)!
Have you had any problem not covered in this README? Do you want
to see other embedding examples?
Let us know by [creating an issue](https://github.com/flutter/samples/issues/new) or opening a new pull request.
Thanks!