# Flutter/Dart: Simplifying Isolate and Worker Usage

By using the [isolate\_manager v5.0.0](https://pub.dev/packages/isolate_manager), the Isolate on the VM and Worker on the Web will be implemented more easily than ever.

This package uses `js_interop` and the `web` package under the hood, so the app can freely compile to WASM.

Firstly, add an annotation to a function that you want to use as a Worker:

```dart
@isolateManagerWorker
int add(List<int> params){
  return params[0] + params[1]
}

@isolateManagerWorker
int subtract(List<int> params) {
  return params[0] - params[1];
}
```

Note that those functions can not be depended on any Flutter UI library like `dart:ui` or `dart:io` which are not supported when compiling to `js`.

Then create an `IsolateManager` instance:

```dart
final isolatedAdd = IsolateManager.create(
                      add, 
                      workerName: 'add', 
                      concurrent: 2,
                   );

final isolatedSubtract = IsolateManager.create(
                      subtract, 
                      workerName: 'subtract', 
                      concurrent: 2,
                   );
```

Run this command to generate the Workers:

```bash
dart run isolate_manager:generate
```

Now we can use it to compute something like:

```dart
final addResult = await isolatedAdd([50, 30]); // 80
final subtractResult = await isolatedSubtract([50, 30]); //20
```

Or

```dart
StreamBuilder(
  stream: isolatedAdd.stream,
  builder: (context, snapshot) {
    if (!snapshot.hasData) {
      return const Center(
        child: CircularProgressIndicator(),
      );
    }
    return Text('Isolated Add: ${snapshot.data}');
  },
),
```

That’s it. Those isolated functions will work on both VM (via Isolate) and Web (via Worker).

Thank you for your reading.