SkillsAdd

github/awesome-copilot

react18-lifecycle-patterns

Provides exact before/after migration patterns for the three unsafe class component lifecycle methods - componentWillMount, componentWillReceiveProps, and componentWillUpdate - targeting React 18.3.1. Use this skill whenever a class component needs its lifecycle methods migrated, when deciding between getDerivedStateFromProps vs componentDidUpdate, when adding getSnapshotBeforeUpdate, or when fixing React 18 UNSAFE_ lifecycle warnings. Always use this skill before writing any lifecycle migratio…

First seen Apr 9, 2026

Installation

$ npx skills add github/awesome-copilot --skill react18-lifecycle-patterns
View on skills.sh ↗ GitHub repository ↗

Summary

  • Provides exact before/after migration patterns for the three unsafe class component lifecycle methods - componentWillMount, componentWillReceiveProps, and componentWillUpdate - targeting React 18.3.1.
  • Use this skill whenever a class component needs its lifecycle methods migrated, when deciding between getDerivedStateFromProps vs componentDidUpdate, when adding getSnapshotBeforeUpdate, or when fixing React 18 UNSAFE_ lifecycle warnings.
  • Always use this skill before writing any lifecycle migration code - do not guess the pattern from memory, the decision trees here prevent the most common migration mistakes.

Similar popular skills

Related neighbors and high-traction skills in the same topics — useful to compare before installing.

vercel-react-best-practices Same topic
vercel-labs/agent-skills 697.8K installs
azure-hosted-copilot-sdk Same topic
microsoft/azure-skills 440.4K installs
vercel-composition-patterns Same topic
vercel-labs/agent-skills 326.5K installs
supabase Same topic
supabase/agent-skills

Use when doing ANY task involving Supabase. Triggers: Supabase products (Database, Auth, Edge F…

263K installs
vercel-react-native-skills Same topic
vercel-labs/agent-skills 205.5K installs
vercel-react-view-transitions Same topic
vercel-labs/agent-skills 115.9K installs

Also in this package

Other skills from github/awesome-copilot · top by installs.

npx skills add github/awesome-copilot
git-commit 44.5K excalidraw-diagram-generator 29.1K documentation-writer 26.2K multi-stage-dockerfile 23.4K prd 22.9K gh-cli 21.9K refactor 21.6K java-springboot 19.9K create-readme 18.1K playwright-generate-test 18K

Browse all from github/awesome-copilot

More details

Agent compatibility

Declared targets from SKILL.md / docs. Unmarked agents are not listed — the skill may still install via the CLI.

Claude Code Not declared
Cursor Not declared
Codex Not declared
GitHub Copilot Declared
Windsurf Not declared
Gemini CLI Not declared
Cline Not declared
OpenCode Not declared

Repository health

Stars 38.8K
License LICENSE
Default branch main
Open issues 21
Status Active

Skill metadata

Parsed from SKILL.md frontmatter.

Declared agents github-copilot

Package contents

Files included with this skill beyond the listing page.

  • skill md SKILL.md 3,653 B
  • docs SUMMARY.md 647 B

History

  1. First seen on skills.sh
  2. First recorded snapshot · 795 installs

SKILL.md

React 18 Lifecycle Patterns

Reference for migrating the three unsafe class component lifecycle methods to React 18.3.1 compliant patterns.

Quick Decision Guide

Before migrating any lifecycle method, identify the semantic category of what the method does. Wrong category = wrong migration. The table below routes you to the correct reference file.

componentWillMount - what does it do?

What it does Correct migration Reference
Sets initial state (this.setState(...)) Move to constructor [→ componentWillMount.md](references/componentWillMount.md#case-a)
Runs a side effect (fetch, subscription, DOM) Move to componentDidMount [→ componentWillMount.md](references/componentWillMount.md#case-b)
Derives initial state from props Move to constructor with props [→ componentWillMount.md](references/componentWillMount.md#case-c)

componentWillReceiveProps - what does it do?

What it does Correct migration Reference
Async side effect triggered by prop change (fetch, cancel) componentDidUpdate [→ componentWillReceiveProps.md](references/componentWillReceiveProps.md#case-a)
Pure state derivation from new props (no side effects) getDerivedStateFromProps [→ componentWillReceiveProps.md](references/componentWillReceiveProps.md#case-b)

componentWillUpdate - what does it do?

What it does Correct migration Reference
Reads the DOM before update (scroll, size, position) getSnapshotBeforeUpdate [→ componentWillUpdate.md](references/componentWillUpdate.md#case-a)
Cancels requests / runs effects before update componentDidUpdate with prev comparison [→ componentWillUpdate.md](references/componentWillUpdate.md#case-b)

The UNSAFE_ Prefix Rule

Never use UNSAFEcomponentWillMount, UNSAFEcomponentWillReceiveProps, or UNSAFE_componentWillUpdate as a permanent fix.

Prefixing suppresses the React 18.3.1 warning but does NOT:

  • Fix concurrent mode safety issues
  • Prepare the codebase for React 19 (where these are removed, with or without the prefix)
  • Fix the underlying semantic problem the migration is meant to address

The UNSAFE prefix is only appropriate as a temporary hold while scheduling the real migration sprint. Mark any UNSAFE prefix additions with:

// TODO: React 19 will remove this. Migrate before React 19 upgrade.
// UNSAFE_ prefix added temporarily - replace with componentDidMount / getDerivedStateFromProps / etc.

Reference Files

Read the full reference file for the lifecycle method you are migrating:

  • references/componentWillMount.md - 3 cases with full before/after code
  • references/componentWillReceiveProps.md - getDerivedStateFromProps trap warnings, full examples
  • references/componentWillUpdate.md - getSnapshotBeforeUpdate + componentDidUpdate pairing

Read the relevant file before writing any migration code.