chrome-extension-developer

Define a manifest.json with manifest_version 3, register a background service worker instead of a background page, and declare content scripts with match patterns. Use chrome.runtime messaging to connect the service worker, content scripts, and popup pages.

Replace persistent background pages with an ephemeral service worker, move network request blocking to declarativeNetRequest, and update host permissions into the host_permissions field. Replace setTimeout scheduling with chrome.alarms since service workers can be terminated.

Manifest V3 service workers are ephemeral and become inactive after idle periods, killing timers and in-memory state. Use chrome.alarms for scheduled tasks and chrome.storage.local or chrome.storage.sync for persistent data instead of in-memory variables.

Use chrome.runtime.sendMessage from the content script and chrome.runtime.onMessage.addListener in the service worker. Return true from the listener to keep the message channel open for asynchronous sendResponse calls.

No, localStorage is unavailable in service workers. Use chrome.storage.local for device-specific data or chrome.storage.sync for data synchronized across the user's signed-in browsers.