As their methods are invoked in the components React?

I have the following code, there is a component in which two methods componentDidMount, componentWillUnmount, one cyclically updates the status, the other ceases to update how they work, if not explicitly called. Code - creates a time, and continuously updates the status time.
class Clock extends React.Component {
 constructor(props) {
super(props);
 this.state = {date: new Date()};
}

 componentDidMount() {
 this.timerID = setInterval(
 () => this.tick(),
1000
);
}

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

 tick() {
this.setState({
 date: new Date()
});
}

 render() {
 return (
the <div>
 <h1>Hello, world!</h1>
 <h2>It is {this.state.date.toLocaleTimeString()}.</h2>
</div>
);
}
}

ReactDOM.render(
<clock>,
document.getElementById('root')
);</clock>
June 27th 19 at 15:14
1 answer
June 27th 19 at 15:16
tick is called every second, and in his body there is a setState, which after work, automatically calls the render () method. So every second is rerender your component

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