MyTimer

import React, { Component } from 'react';

class Timer extends Component {
    constructor(props){
        super(props);
        this.state={valeur:0}


    }


    componentDidMount() {
        const coucou = setInterval(() => {
            console.log(this.state.valeur)
            this.setState({valeur: this.state.valeur + 1})}, 1000)
           }
    
    

    componentWillUpdate() {
        console.log('Un update a eu lieu');
    }
    componentWillUnmount() {
        clearInterval(this.state.coucou);
      }
    
    render() {
        
        return (
            <div>
        <h1>{this.state.valeur}</h1>
        <button onClick={this.props.onExit}>Start</button>
      </div>
        );
    }
}


export default Timer;