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30 lines
507 B
30 lines
507 B
class Timer extends React.Component {
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constructor(props) {
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super(props);
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this.state = { seconds: 0 };
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}
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tick() {
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this.setState(prevState => ({
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seconds: prevState.seconds + 1
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}));
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}
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componentDidMount() {
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this.interval = setInterval(() => this.tick(), 1000);
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}
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componentWillUnmount() {
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clearInterval(this.interval);
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}
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render() {
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return (
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<div>
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Seconds: {this.state.seconds}
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</div>
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);
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}
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}
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ReactDOM.render(<Timer />, mountNode);
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