npx create-react-app redux-counter
cd redux-counter
npm install –save redux react-redux
Creamos Counter.js:
import React from 'react';
class Counter extends React.Component {
state = { count: 0 }
increment = () => {
this.setState({
count: this.state.count + 1
});
}
decrement = () => {
this.setState({
count: this.state.count - 1
});
}
render() {
return (
<div>
<h2>Counter</h2>
<div>
<button onClick={this.decrement}>-</button>
<span>{this.state.count}</span>
<button onClick={this.increment}>+</button>
</div>
</div>
)
}
}
export default Counter;
Después de modificarlo:
import React from 'react';
import { connect } from 'react-redux';
function mapStateToProps(state) {
return {
count: state.count
};
}
class Counter extends React.Component {
//state = { count: 0 }
increment = () => {
this.props.dispatch({ type: "INCREMENT" });
}
decrement = () => {
this.props.dispatch({ type: "DECREMENT" });
}
render() {
return (
<div>
<h2>Counter</h2>
<div>
<button onClick={this.decrement}>-</button>
<span>{this.props.count}</span>
<button onClick={this.increment}>+</button>
</div>
</div>
)
}
}
export default connect(mapStateToProps)(Counter);
App
import React from 'react';
import logo from './logo.svg';
import './App.css';
import Counter from './Counter';
import { createStore } from 'redux';
import { Provider } from 'react-redux';
const initialState = {
count: 0
};
function reducer(state = initialState, action) {
console.log('reducer', state, action);
switch (action.type) {
case 'INCREMENT':
return {
count: state.count + 1
};
case 'DECREMENT':
return {
count: state.count - 1
};
case 'RESET':
return {
count: 0
};
default:
return state;
}
}
const store = createStore(reducer);
function App() {
return (
<Provider store={store}>
<Counter />
</Provider>
);
}
export default App;