A Firefox extension that automatically converts Japanese Yen prices to USD on Amazon Japan (amazon.co.jp).
This extension is now available on the FireFox Addon Store. https://addons.mozilla.org/en-US/firefox/addon/amazon-japan-usd-converter/#
- Real-time currency conversion using current exchange rates
- Toggle between two display modes:
- Show both currencies (¥1000 ($6.37))
- Show USD only ($6.37)
- Automatically converts all prices on the page
- Updates dynamically when new content loads
- Simple toolbar popup for easy settings
- Caches exchange rates locally
- Updates exchange rates every 6 hours
- Fallback rate if API is unavailable
- Visit Amazon Japan USD Converter on Firefox Add-ons
- Click "Add to Firefox"
- Clone this repository
- Open Firefox and navigate to
about:debugging
- Click "This Firefox" on the left sidebar
- Click "Load Temporary Add-on"
- Select any file in the extension's directory
- Visit Amazon Japan
- Prices will automatically convert to USD
- Click the extension icon in the toolbar to:
- Switch between display modes
- See current exchange rate
- Manually refresh the exchange rate
- Uses exchangerate-api.com for live currency rates
- Default fallback rate: 157 JPY = 1 USD
- Caches exchange rates in browser storage
- Updates rates every 6 hours
- Uses MutationObserver for dynamic content
manifest.json
: Extension configurationconverter.js
: Main conversion logicpopup.html
: Settings UIpopup.js
: Settings functionalityicon.svg
: Vector icon sourceicon48.png
,icon96.png
: Extension icons
To create the extension package:
- Select all files
- Create a ZIP archive
- Ensure manifest.json is at the root level of the ZIP
MIT License - See LICENSE file for details
- Fork the repository
- Create your feature branch
- Commit your changes
- Push to the branch
- Create a Pull Request
If you encounter any issues or have suggestions, please open an issue on GitHub.