Programming Tutorials

  You have upgraded your Flutter project to the latest version. You are ready to unlock the performance gains of WebAssembly (Wasm) by running   flutter build web --wasm . Instead of a successful build, the compiler halts with a blocking error: Error: Dart library 'dart:html' is not available on this platform. This error is the single most common blocker for Flutter developers migrating to Wasm. It occurs because the legacy  dart:html  library relies on dynamic JavaScript interop mechanisms that are incompatible with the strict typing required by WasmGC (Garbage Collection). To compile to Wasm, you must migrate your code from  dart:html  and  dart:js  to the modern  package:web  and  dart:js_interop . This guide details the root cause and provides the precise code refactoring required to fix it. The Root Cause: Why  dart:html  Is Incompatible with Wasm Historically, Flutter Web (via the  dart2js  compiler) intera...