Extension.js features overview
Understand the core platform capabilities that make Extension.js practical for real-world browser extension development.
Feature chooser
| Goal | Start here |
|---|---|
| Ship one codebase to multiple browsers | Cross-browser compatibility |
| Handle browser-specific manifest differences | Browser-specific manifest fields |
| Keep non-manifest assets organized | Special folders |
| Manage environment-specific behavior | Environment variables |
| Centralize build/runtime defaults | Extension configuration |
| Extend bundler behavior safely | Rspack configuration |
| Understand update behavior in dev mode | Page reload and HMR |
| Avoid path drift between source and output | Path resolution |
| Build and package for target matrices | Multi-platform builds |
Recommended progression
- Validate browser output guarantees (
cross-browser-compatibility). - Lock project defaults (
extension-configuration). - Add advanced behavior (
rspack-configuration,environment-variables). - Optimize release flows (
multi-platform-builds).
Video walkthrough
Next steps
- Apply these capabilities in Workflows.
- Choose the right execution command in Commands reference.
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