react18-legacy-context

Included with Lifetime

$97 forever

Provides the complete migration pattern for React legacy context API (contextTypes, childContextTypes, getChildContext) to the modern createContext API. Use this skill whenever migrating legacy context in class components - this is always a cross-file migration requiring the provider AND all consumers to be updated together. Use it before touching any contextTypes or childContextTypes code, because migrating only the provider without the consumers (or vice versa) will cause a runtime failure. Always read this skill before writing any context migration - the cross-file coordination steps here prevent the most common context migration bugs.

Web Dev

What this skill does


# React 18 Legacy Context Migration

Legacy context (`contextTypes`, `childContextTypes`, `getChildContext`) was deprecated in React 16.3 and warns in React 18.3.1. It is **removed in React 19**.

## This Is Always a Cross-File Migration

Unlike most other migrations that touch one file at a time, context migration requires coordinating:
1. Create the context object (usually a new file)
2. Update the **provider** component
3. Update **every consumer** component

Missing any consumer leaves the app broken - it will read from the wrong context or get `undefined`.

## Migration Steps (Always Follow This Order)

```
Step 1: Find the provider (childContextTypes + getChildContext)
Step 2: Find ALL consumers (contextTypes)
Step 3: Create the context file
Step 4: Update the provider
Step 5: Update each consumer (class components → contextType, function components → useContext)
Step 6: Verify - run the app, check no legacy context warnings remain
```

## Scan Commands

```bash
# Find all providers
grep -rn "childContextTypes\|getChildContext" src/ --include="*.js" --include="*.jsx" | grep -v "\.test\."

# Find all consumers
grep -rn "contextTypes\s*=" src/ --include="*.js" --include="*.jsx" | grep -v "\.test\."

# Find this.context usage (may be legacy or modern - check which)
grep -rn "this\.context\." src/ --include="*.js" --include="*.jsx" | grep -v "\.test\."
```

## Reference Files

- **`references/single-context.md`** - complete migration for one context (theme, auth, etc.) with provider + class consumer + function consumer
- **`references/multi-context.md`** - apps with multiple legacy contexts (nested providers, multiple consumers of different contexts)
- **`references/context-file-template.md`** - the standard file structure for a new context module

Files: 4

Size: 16.4 KB

Complexity: 37/100

Category: Web Dev

Source: https://github.com/github/awesome-copilot/tree/main/plugins/react18-upgrade/skills/react18-legacy-context

Related in Web Dev

generating-lwc-components

Included

Lightning Web Components with PICKLES methodology and 165-point scoring. Use this skill when the user creates or edits LWC components, builds wire service patterns, or writes Jest tests for LWC. TRIGGER when: user creates/edits LWC components, touches lwc/**/*.js, .html, .css, .js-meta.xml files, or asks about wire service, SLDS, or Jest LWC tests. DO NOT TRIGGER when: Apex classes (use generating-apex), Aura components, or Visualforce.

Web Devscripts

tanstack-query

Included

Manage server state in React with TanStack Query v5. Set up queries with useQuery, mutations with useMutation, configure QueryClient caching strategies, implement optimistic updates, and handle infinite scroll with useInfiniteQuery. Use when: setting up data fetching in React projects, migrating from v4 to v5, or fixing object syntax required errors, query callbacks removed issues, cacheTime renamed to gcTime, isPending vs isLoading confusion, keepPreviousData removed problems.

Web Devscripts

document-processor-api

Included

Process documents with Nutrient DWS. Use when the user wants to generate PDFs from HTML or URLs, convert Office/images/PDFs, assemble or split packets, OCR scans, extract text/tables/key-value pairs, redact PII, watermark, sign, fill forms, optimize PDFs, or produce compliance outputs like PDF/A or PDF/UA. Triggers include convert to PDF, merge these PDFs, OCR this scan, extract tables, redact PII, sign this PDF, make this PDF/A, or linearize for web delivery.

Web Devscripts

nutrient-document-processing

Included

Web Devscripts

tanstack-query

Included

Manage server state in React with TanStack Query v5. Covers useMutationState, simplified optimistic updates, throwOnError, network mode (offline/PWA), and infiniteQueryOptions. Use when setting up data fetching, fixing v4→v5 migration errors (object syntax, gcTime, isPending, keepPreviousData), or debugging SSR/hydration issues with streaming server components.

Web Devscripts

accelint-nextjs-best-practices

Included

Next.js performance optimization and best practices. Use when writing Next.js code (App Router or Pages Router); implementing Server Components, Server Actions, or API routes; optimizing RSC serialization, data fetching, or server-side rendering; reviewing Next.js code for performance issues; fixing authentication in Server Actions; or implementing Suspense boundaries, parallel data fetching, or request deduplication.

Web Devscripts