reactStrictMode

Core Idea

Opts the Pages Router into React's Strict Mode, a dev-only feature that highlights unsafe lifecycles, legacy API usage and other potential problems.

Key Concepts

• reactStrictMode: boolean in next.config.js. Since Next.js 13.5.1, true by default for App Router; still needs explicit opt-in for Pages Router.
• React.StrictMode: can be applied incrementally, page-by-page, without setting the global flag.

Code Examples

module.exports = {
  reactStrictMode: true,
}

• O que demonstra: habilita Strict Mode globalmente para o Pages Router.

Key Takeaways

1. App Router já vem com Strict Mode true desde a v13.5.1, essa config só importa pro Pages Router.
2. Pode desabilitar com reactStrictMode: false mesmo no App Router se necessário.
3. Adoção incremental é possível via <React.StrictMode> em páginas específicas.

Connects To

• React Strict Mode (react.dev): fonte da funcionalidade em si, Next.js só expõe o toggle.