Focus Timer

A lightweight focus timer built with vanilla JavaScript, designed around a clear state machine with persistent session data.

Live Demo
👉 https://selladurais.github.io/focus-timer/

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Why this project?

This project was built to demonstrate clean state management, predictable timer behavior, and data persistence without relying on frameworks.

The focus was correctness, edge-case handling, and maintainable logic rather than UI libraries.

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Core Features

• Deterministic Start / Pause / Resume flow
• Configurable focus session duration
• Distraction tracking per session
• Persistent session history with timestamps
• Derived statistics (total focus time, sessions, average distractions)
• LocalStorage-based persistence
• Dark / Light mode
• Mobile-friendly layout

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Technical Highlights

• Explicit state machine for timer control
• Defensive handling of pause/resume edge cases
• Derived state calculated without mutating core logic
• No framework abstractions — plain JavaScript only

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Tech Stack

• HTML5
• CSS3 (CSS variables, dark mode)
• Vanilla JavaScript

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How to Run

1. Clone or download the repository
2. Open index.html in any modern browser
3. No build tools or dependencies required

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Version

v1.1 (Frozen)

This version is intentionally frozen after implementing derived session statistics without modifying the original state logic.