ReFocus
A Chrome extension that tracks time spent on social media and nudges you to refocus with a rolling-window alert system.
Screenshots
About This Project
ReFocus is a Chrome extension I built to solve a personal problem: I was spending more time on social media than I intended, and I had no real sense of how much. The extension tracks time on any domain you configure, and alerts you when you exceed a threshold — with a full-screen overlay, a system notification, and an audio chime, all firing in parallel so you can’t easily ignore it.
Features
- Rolling-window tracking — thresholds are evaluated against a sliding time window (e.g. “30 minutes in the last 60 minutes”), not a fixed daily reset, so overuse is caught in real time
- Full-screen overlay — a Shadow DOM overlay that displays your recent usage stats and a countdown; requires interaction before dismissal
- Configurable sites — add any domain; custom labels and colours per site;
twitter.comis normalised tox.comautomatically - Popup stats — shows today, yesterday, and 7-day rolling average at a glance, with a live session indicator
- Options page — configure tracked sites, alert threshold, observation window, and cooldown period
- i18n — UI follows the browser’s language setting; Traditional Chinese and English supported
- System theme — dark/light mode follows the OS setting
Architecture
Pure Manifest V3 Chrome Extension — no framework, no build step. The entire logic lives in background.js as a Service Worker.
Because Service Workers can be terminated at any time by Chrome, all state is persisted to chrome.storage.local rather than in-memory globals. A heartbeat alarm writes a checkpoint every minute as crash protection; stopTracking() commits the full {start, end} session to usageStats when the tab loses focus.
Alert evaluation uses a rolling window: each checkAlert() call computes the intersection of stored sessions with the window [now − N minutes, now], summing across all tracked domains. There is no fixed reset point — time simply slides out of the window naturally.
Audio playback runs in a dedicated Offscreen Document, since the Web Audio API is unavailable in a Service Worker context.