Mousewho

Mousewho is a Manifest V3 browser extension for fast keyboard-only browsing with Vim-style keys. It avoids persistent overlays and only scans the visible page when link hints are requested.

Load in Chrome

1. Open chrome://extensions.
2. Enable Developer mode.
3. Click Load unpacked and choose this repository.

Load in Firefox

1. Run npm run build:firefox.
2. Open about:debugging#/runtime/this-firefox.
3. Click Load Temporary Add-on and choose dist/firefox/manifest.json.

Keys

Key	Action
j / k	Scroll down / up
h / l	Scroll left / right
d / u	Half-page down / up
gg / G	Top / bottom of page
f	Show fast hints and click the selected target
F	Show hints and open the selected link in a background tab
J / K	Previous / next tab
i	Focus first visible text input and enter insert mode
?	Show in-page help
Esc / Ctrl-[	Exit hints/help or blur focused input from insert mode

Performance approach

• Normal scrolling and navigation are direct keydown handlers with no page scans.
• Link/button hinting is lazy: Mousewho scans only when f/F is pressed.
• Candidate collection uses one selector query, filters to visible targets, caps rendered hints, and builds DOM markers in a DocumentFragment.
• Overlays live in a contained Shadow DOM host with pointer-events: none for hints.
• Synthetic benchmark coverage tracks hint label generation and prefix filtering latency.

Development

npm test
npm run build:firefox
npm run benchmark

The Chrome extension has no runtime build step. The Firefox build copies shared source files into dist/firefox with a Firefox-specific manifest. There are no npm dependencies.