Currently, Flutter Web apps launch as soon as their main.dart.js is loaded and parsed. This makes it harder for web developers to integrate Flutter web apps into their sites (for example, it's hard to create a progress bar while the app is loading, or prevent a flutter app from using resources until it's really needed).

Let's introduce a Flutter Web bootstrap API that lets developers control how (when) the bulk of the Flutter web app is downloaded, and run.

Use case

• Users want to control when a Flutter web app starts utilizing computing resources (network, processor) on their web app.
• Ability to create a somewhat accurate "loading" bar.
• Increase Lighthouse scores by converting Flutter web apps into something that can be asynchronously loaded and run.

Proposal

• Design doc: 📄 Programmatic Bootstrap of a Flutter Web App
• PoC: Demo