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React Native Academy · Lección

Consumo de contexto con useContext

Lea valores del contexto dentro de cualquier componente anidado mediante el hook useContext, sin necesidad de pasar props a través de componentes intermedios.

Consumo de contexto con useContext es una lección gratuita de React Native Academy en CoddyKit. Esta es la lección 2 de 4. Puedes leer la lección completa abajo gratuitamente — luego la practicas en el navegador con un editor de código integrado y un tutor de IA 24/7. Forma parte de la ruta de aprendizaje de React Native Academy, y tu progreso se sincroniza en la web y la app de CoddyKit. El curso de React Native Academy incluye 4 lecciones en total.

Partes de esta lección aún no han sido traducidas y se muestran en inglés.

Reading Context with useContext

The useContext(ContextObject) hook lets any function component subscribe to a context and read its current value. It replaces the older Consumer render prop pattern with a simple hook call. The component automatically re-renders whenever the context value changes.

import { useContext } from 'react';
import { ThemeContext } from '../context/ThemeContext';

function Header() {
  const { theme } = useContext(ThemeContext);

  return (
    <View style={{ backgroundColor: theme === 'dark' ? '#1a1a2e' : '#fff' }}>
      <Text>My App</Text>
    </View>
  );
}

No Prop Drilling Required

The main benefit of useContext is that the consuming component does not need to receive props from its parent. The Header component in the previous example can be anywhere in the tree — three levels deep, inside a modal, or in a completely different branch — and it still reads the same theme value directly from context.

// Without context: theme prop drills through App→Screen→Section→Card→Header
// With context: Header reads theme directly from context
function DeepComponent() {
  const { user } = useContext(AuthContext); // no props needed
  return <Text>Welcome, {user.name}</Text>;
}

Calling Actions from Context

Context can expose not just data but also functions that update the data. Call these functions directly from the consuming component without knowing where the state lives. The Provider handles the state update and all consumers that depend on the value re-render automatically.

function LogoutButton() {
  const { logout } = useContext(AuthContext);

  return (
    <Button title='Sign Out' onPress={logout} />
  );
}

Using Multiple Contexts in One Component

A component can consume multiple contexts by calling useContext multiple times with different context objects. Each call is independent — a change in ThemeContext only causes re-renders in ThemeContext consumers, not in AuthContext consumers (unless they also depend on ThemeContext).

function ProfileScreen() {
  const { user } = useContext(AuthContext);
  const { theme } = useContext(ThemeContext);

  return (
    <View style={styles[theme]}>
      <Text style={styles[theme + 'Text']}>
        {user.name}
      </Text>
    </View>
  );
}

Context Value is the Latest Render

useContext always gives you the most recent value provided by the nearest matching Provider. When the Provider re-renders with a new value, React propagates the update to all consumers immediately, even if intermediate components between the Provider and consumer did not re-render. This is one of the key advantages over passing props through potentially non-rendering intermediaries.

Creating a useAuth Custom Hook

Instead of importing and calling useContext(AuthContext) in every component, wrap it in a custom useAuth hook. This abstracts away the context object import, makes the calling code more readable, and lets you add error checks or derived values in one place.

// context/AuthContext.js
export function useAuth() {
  const ctx = useContext(AuthContext);
  if (!ctx) throw new Error('useAuth must be inside AuthProvider');
  return ctx;
}

// In any component
function NavBar() {
  const { user, logout } = useAuth(); // clean and simple
  return <Text>{user.email}</Text>;
}

Guarding Routes with Context

A common pattern is to read auth state from context and conditionally render either the authenticated app stack or the login screen. The root navigator reads the user from AuthContext — when user is null it renders the auth screens, and when it is set it renders the main app screens.

function RootNavigator() {
  const { user } = useAuth();

  return (
    <NavigationContainer>
      {user ? <AppStack /> : <AuthStack />}
    </NavigationContainer>
  );
}

Conditional Rendering Based on Context

Components can use context values to make render decisions. A premium feature component checks the user's subscription tier from context and renders either the full feature or a paywall CTA. This logic lives in the consuming component, keeping the Provider generic and reusable.

function PremiumFeature({ children }) {
  const { user } = useAuth();
  const isPro = user?.subscription === 'pro';

  if (!isPro) {
    return <UpgradePrompt />;
  }

  return children;
}

Context in List Items

Context works inside FlatList renderItem components too. Each list item can read from context without props. Be mindful that if the context value changes, every visible list item will re-render — use React.memo and ensure the context value is stable (memoized) to mitigate the impact.

const CartItem = React.memo(({ item }) => {
  const { addToCart } = useContext(CartContext);

  return (
    <View style={styles.row}>
      <Text>{item.name}</Text>
      <Button title='Add' onPress={() => addToCart(item)} />
    </View>
  );
});

Context vs Props: When to Use Each

Use props for data that is naturally owned by the parent and directly relevant to the child's display. Use context for global or cross-cutting concerns: authentication, theme, language, cart state. Over-using context for local data makes components harder to understand and reuse in isolation, because their dependencies are implicit rather than explicit.

The useContext Return Value

useContext returns exactly the value passed to the nearest Provider's value prop. If no Provider is found above the component, it returns the default value given to createContext(). Destructure the returned object directly at the call site for cleaner, more readable code.

// Full value object
const themeContext = useContext(ThemeContext);
themeContext.theme; // 'light' or 'dark'

// Destructured (preferred)
const { theme, toggleTheme } = useContext(ThemeContext);

// From custom hook
const { user, login, logout } = useAuth();

Quick Check

Test your understanding of consuming context with useContext from this lesson.

Lesson Recap

In this lesson you learned: useContext(ContextObject) reads the nearest Provider's value without prop drilling, a component can consume multiple contexts by calling useContext multiple times, and wrapping useContext in a custom hook gives a clean API with error checking. Next up we build a theme context with a dark mode toggle.

Preguntas frecuentes

¿La lección «Consumo de contexto con useContext» es gratis?

Sí — el texto completo de «Consumo de contexto con useContext» es gratis para leer aquí en la web. Para practicarla de forma interactiva (editor de código integrado y tutor de IA 24/7) y desbloquear el resto del curso de React Native Academy, actualiza a CoddyKit PRO. El curso de React Native Academy incluye 4 lecciones en total.

¿Qué aprenderé en «Consumo de contexto con useContext»?

Lea valores del contexto dentro de cualquier componente anidado mediante el hook useContext, sin necesidad de pasar props a través de componentes intermedios. Practicas React Native Academy con código real que ejecutas directamente en el navegador, y un tutor de IA 24/7 responde tus preguntas mientras trabajas en la lección.

¿Necesito experiencia previa para empezar React Native Academy?

No se requiere experiencia previa. React Native Academy en CoddyKit está estructurado para principiantes hasta estudiantes avanzados, así que puedes empezar aquí o desde el inicio y avanzar a tu ritmo. Esta es la lección 2 de 4.

¿Cuánto tiempo toma la lección «Consumo de contexto con useContext»?

La mayoría de las lecciones de CoddyKit toman alrededor de 5–10 minutos. Cada una es compacta e interactiva, así que avanzas constantemente y retomas exactamente por donde dejaste en la web y la app.

¿Puedo escribir y ejecutar código en esta lección de React Native Academy?

Sí. Cada lección de React Native Academy incluye un editor de código integrado, así que escribes y ejecutas código real directamente en tu navegador y obtienes retroalimentación instantánea de IA — sin configuración local necesaria.

Todas las lecciones de este curso

  1. Creación y provisión de un contexto
  2. Consumo de contexto con useContext
  3. Un contexto de tema con alternancia del modo oscuro
  4. Cómo evitar problemas de rendimiento del contexto
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