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// Chrome Extension · JavaScript · Web Scraping · Push Notifications

Price Alert Chrome Extension

Smart Chrome extension that monitors e-commerce product prices and fires browser push notifications the moment a price drops to your set target.

Platform: Chrome Extension
Language: JavaScript

Overview

A Chrome extension for deal hunters. Users visit any product page on supported e-commerce sites, click the extension icon, set a target price, and the extension monitors the price in the background. When the price drops to or below the target, a Chrome push notification fires immediately — with a direct link back to the product page to purchase.

Tech Stack

JavaScript (ES6+)Chrome Extension Manifest V3Chrome Alarms APIChrome Notifications APIContent ScriptsService WorkerWeb Scraping

Key Contributions

  • Manifest V3 service worker architecture — background price checks run via Chrome Alarms API without keeping a persistent background page.
  • Content script injects into product pages to extract price using CSS selector heuristics adapted per site.
  • Chrome Storage Sync for persisting tracked products across devices on the same Chrome account.
  • Price parsing handles currency symbols, comma-separated thousands, and localized decimal formats.
  • Badge count on extension icon shows number of active price watches at a glance.

Screenshots

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Results

Migrating to Manifest V3 from V2 patterns was the hardest part — service worker lifecycles required rethinking how state was retained between alarm firings. Chrome Storage became the single source of truth.