Redux middleware

Redux Middleware is mechanism for extending Redux functionality that allows injecting additional logic between action dispatch and moment when it reaches reducer.

What Middleware is For

Middleware in Redux is used for:

Processing async operations
Logging actions
Error handling
Modifying actions before they reach reducer
Canceling actions

How Middleware Works

Middleware sits between dispatch and reducer, allowing to:

Intercept actions
Modify actions
Create new actions
Stop actions

Simple Middleware Example

javascript

const loggerMiddleware = store => next => action => {
  console.log('Previous state:', store.getState());
  console.log('Action:', action);
  
  const result = next(action);
  
  console.log('Next state:', store.getState());
  return result;
};

// Connecting middleware
const store = createStore(
  rootReducer,
  applyMiddleware(loggerMiddleware)
);

Popular Middleware

Redux Thunk: For async operations
Redux Saga: For complex async flows
Redux Observable: For reactive programming
Redux Logger: For debugging

Important: Middleware should be used only when really necessary, as each additional middleware increases application complexity.

Content

What Middleware is ForHow Middleware WorksSimple Middleware ExamplePopular Middleware

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Redux middleware

#What Middleware is For

#How Middleware Works

#Simple Middleware Example

#Popular Middleware