Amazon Wishlist Price Drop Alert

WHAT IT DOES

This script monitors your Amazon wishlist for price drops and highlights items that have decreased in price. When you view your wishlist, the script extracts each item's current price, title, and ASIN, and compares it to the price when the item was added to the list or to a previously stored price. Items with price drops receive a visual highlight with a green border and a badge showing the exact percentage drop. The highlight intensity is proportional to the drop percentage—larger drops get more prominent highlighting. A summary banner at the top of the wishlist shows the total number of items, how many have dropped in price, and the largest drop found. When a price drop exceeds your configured threshold, a desktop notification alerts you so you can act on the deal quickly. The script also persists price history locally across visits, so you can track drops over time even if you don't manually check your wishlist every day.

WHERE IT RUNS

The script runs on all major Amazon domains, including .com, .co.uk, .ca, .de, .fr, .it, .es, .com.au, and .co.jp. It works on wishlist pages (including /wishlist/, /gp/registry/, and /hz/wishlist/) and on any page that displays wishlist items. It handles both desktop and mobile views, and dynamically processes new items as they load via scrolling or pagination.

HOW TO USE

After installation, the settings panel appears on the left side of the screen with the gear emoji (⚙️). Open the panel to configure the script:

- The "Enable price drop alerts" toggle enables or disables the monitoring. When enabled, items with price drops are highlighted and notifications are shown.

- Set a notification threshold percentage in the input field (default 10%). When an item drops by at least this percentage, a desktop notification appears.

- Choose a highlight color using the color picker (default green).

- Click "Refresh wishlist" to manually re-scan all items and update highlights.

- Click "Reset price history" to clear all stored price data and start fresh.

The script works automatically—just view your wishlist and items with price drops will be highlighted. Click the "🔻 X.X% drop" badge for more details. Notifications appear when significant drops occur, even if you're not actively viewing the wishlist page.

TECHNICAL SECTION — REAL MECHANISM

The script first detects whether the current page is a wishlist page by checking the URL for patterns like /wishlist/, /gp/registry/, or /hz/wishlist/. It then finds wishlist items using selectors such as .a-carousel-card, .g-item-sortable, .a-fixed-left-grid, and [data-reftag], filtering for elements that contain product images, links, or price elements. For each item, it extracts the ASIN from the data-asin attribute, the title from .a-link-normal elements, and the current price by parsing the text of .a-price .a-offscreen or .a-color-price elements using a regular expression that extracts the numeric value. The script also attempts to extract the "Added" price from the wishlist metadata using text containing "Added" and a dollar amount. If no added price is available, the script uses the previously stored price from a local price history object saved via GM_setValue. If no history exists, it sets the added price to the current price and stores it for future comparisons. The drop percentage is calculated as ((addedPrice - currentPrice) / addedPrice) * 100. Items with drops are highlighted with a left border, a subtle background tint, and a badge showing the drop percentage. The badge is inserted after the item title using DOM manipulation (appendChild) and never innerHTML. Price history is stored in a JavaScript object keyed by ASIN and persisted using GM_setValue. A MutationObserver watches for new items being added to the wishlist via scrolling and triggers re-processing.

THE PANEL

The settings panel is built with BotGentz's BGPanel component. It is draggable via its header, allowing you to reposition it anywhere on the screen. The panel snaps to the left edge by default but can be moved freely. Click the gear emoji to collapse the panel into a small bubble, and click the bubble to expand it again. The panel remembers its position per page session. Press the Escape key to quickly close or minimize the panel. The panel includes a status flash bar that provides visual feedback when settings are changed or actions are performed. All settings and price history save automatically via GM_setValue.

PLEASE NOTE

This script requires the free BotGentz browser extension to run. It does not function as a standalone Chrome extension and does not use chrome.* APIs. Amazon frequently updates its wishlist page structure, which may break the selectors used to find items and extract data. If the script stops working, please check for updates. The script stores price history and preferences via GM_setValue. No data is sent externally—all data is stored locally in your browser. The script never reads or writes password fields, hidden inputs, or file inputs. All DOM operations use safe methods (style properties, textContent, appendChild) and never use innerHTML. Notifications require the GM_notification grant and will only work if the BotGentz extension supports desktop notifications.