//src/MyTimer.js


import React, { Component } from "react";




class Clock extends React.Component {

    constructor(props) {
        super(props);
        this.state = {time: 0};
    }


    componentDidMount() {
        this.counter = setInterval(
            () => this.second(),
            1000
        );
    }


    componentWillUnmount() {
        clearInterval(this.counter);
    }


    second() {
        this.setState(
            state => time: state.time + 1
        );
        console.log('un update a eu lieu')
    }


    render() {
        return (
            <div>
                <h1>{this.state.time}</h1>
            </div>
        );
    }
}


ReactDom.render(
    <Clock />
    document.getElementByTd("root")
);