Content Env

Injects a small panel showing the extension's environment values into every web page you visit.

Runs on Chrome, Edge, Firefox · Manifest V3 · Surfaces: content script, background service worker · Styling: CSS · Level: beginner

Create this project

npx extension@latest create my-content-env --template content-env
cd my-content-env
npm install
npm run dev

What it is for

  • Reading build-time configuration inside a content script
  • Switching behavior per browser without touching the source
  • Reference for EXTENSION_PUBLIC_* values in typed sources

First steps

  • Run npm run dev to launch the extension
  • Open any web page to see the panel print the injected values
  • Edit .env.chrome or .env.firefox to change what the panel reads

Permissions it asks for

  • <all_urls>

Source on GitHubDocumentation

extension.devDocumentation for extension.dev