Community WXT Browser Extensions Best Practices

Comprehensive performance optimization guide for WXT browser extension development. Contains 49 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation. Updated for WXT v0.20+.

When to Apply

Reference these guidelines when:

• Writing new WXT browser extension code

• Implementing service worker background scripts

• Injecting content scripts into web pages

• Setting up messaging between extension contexts

• Configuring manifest permissions and resources

Rule Categories by Priority

Priority

Category

Impact

Prefix

1

Service Worker Lifecycle

CRITICAL

svc-

2

Content Script Injection

CRITICAL

inject-

3

Messaging Architecture

HIGH

msg-

4

Storage Patterns

HIGH

store-

5

Bundle Optimization

MEDIUM-HIGH

bundle-

6

Manifest Configuration

MEDIUM

manifest-

7

UI Performance

MEDIUM

ui-

8

TypeScript Patterns

LOW-MEDIUM

ts-

Quick Reference

1. Service Worker Lifecycle (CRITICAL)

• svc-register-listeners-synchronously - Register listeners synchronously to prevent missed events

• svc-avoid-global-state - Use storage instead of in-memory state

• svc-keep-alive-patterns - Keep service worker alive for long operations

• svc-handle-install-update - Handle install and update lifecycle events

• svc-offscreen-documents - Use offscreen documents for DOM operations

• svc-declarative-net-request - Use declarative rules for network blocking

2. Content Script Injection (CRITICAL)

• inject-use-main-function - Place runtime code inside main() function

• inject-choose-correct-world - Select ISOLATED or MAIN world appropriately

• inject-run-at-timing - Configure appropriate runAt timing

• inject-use-ctx-invalidated - Handle context invalidation on update

• inject-dynamic-registration - Use runtime registration for conditional injection

• inject-all-frames - Configure allFrames for iframe handling

• inject-spa-navigation - Handle SPA navigation with wxt:locationchange

3. Messaging Architecture (HIGH)

• msg-type-safe-messaging - Use @webext-core/messaging for type-safe protocols

• msg-return-true-for-async - Return true for async message handlers (raw API)

• msg-use-tabs-sendmessage - Use tabs.sendMessage for content scripts

• msg-use-ports-for-streams - Use ports for streaming communication

• msg-handle-no-receiver - Handle missing message receivers

• msg-avoid-circular-messages - Prevent circular message loops

4. Storage Patterns (HIGH)

• store-use-define-item - Use storage.defineItem for type-safe access

• store-choose-storage-area - Select appropriate storage area

• store-batch-operations - Group related data into single defineItem

• store-watch-for-changes - Use watch() for reactive updates

• store-handle-quota-errors - Handle storage quota errors

• store-versioned-migrations - Use versioning for schema migrations

5. Bundle Optimization (MEDIUM-HIGH)

• bundle-split-entrypoints - Split code by entrypoint

• bundle-analyze-size - Analyze and monitor bundle size

• bundle-tree-shake-icons - Use direct imports for icon libraries

• bundle-externalize-wasm - Load WASM dynamically

• bundle-minify-content-scripts - Minimize content script size

6. Manifest Configuration (MEDIUM)

• manifest-minimal-permissions - Request minimal permissions

• manifest-use-optional-permissions - Use optional permissions progressively

• manifest-web-accessible-resources - Scope web accessible resources

• manifest-content-security-policy - Configure CSP correctly

• manifest-cross-browser-compatibility - Support multiple browsers

7. UI Performance (MEDIUM)

• ui-use-shadow-dom - Use Shadow DOM for injected UI

• ui-defer-rendering - Defer popup rendering until needed

• ui-cleanup-on-unmount - Clean up UI on unmount

• ui-sidepanel-persistence - Preserve sidepanel state

• ui-position-fixed-iframe - Use iframe for complex UI

• ui-avoid-layout-thrashing - Batch DOM reads and writes

8. TypeScript Patterns (LOW-MEDIUM)

• ts-use-imports-module - Use #imports virtual module and auto-imports

• ts-use-browser-not-chrome - Use browser namespace over chrome

• ts-type-entrypoint-options - Type entrypoint options explicitly

• ts-augment-browser-types - Augment types for missing APIs

• ts-strict-null-checks - Enable strict null checks

• ts-import-meta-env - Use import.meta for build info

• ts-avoid-any - Avoid any type in handlers

• ts-path-aliases - Use path aliases for imports

How to Use

Read individual reference files for detailed explanations and code examples:

• Section definitions - Category structure and impact levels

• Rule template - Template for adding new rules

Reference Files

File

Description

references/_sections.md

Category definitions and ordering

assets/templates/_template.md

Template for new rules

metadata.json

Version and reference information