react-egghead.io/Lesson5_Stopwatch.html at master · adamsimonini/react-egghead.io · GitHub

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<head>
    <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
    <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-standalone/6.26.0/babel.min.js"></script>
    <link href="https://fonts.googleapis.com/css?family=Roboto+Slab" rel="stylesheet">
</head>


<style>
    #root{
        display: flex;
        flex-direction: column;
        justify-content: space-around;
        align-items: center;
        color: white;
        background: url('images/darkwood.jpg') no-repeat center;
        background-size: cover;
        font-family: 'Roboto Slab', serif;
    }
    .title{
        font-size: calc(35px + 1vw);
    }
    .mainDiv{
        display: flex;
        flex-direction: column;
        justify-content: space-around;
        align-items: center;
        height: 50vh;
    }
    button{
        border-radius: 50px;
        background: transparent;
        color: white;
        padding: 20px;
        min-width: 100px;
        font-family: 'Roboto Slab', serif;
        font-size: 30px
    }
    label{
        font-size: 35px;
    }
    button:hover{
        cursor: pointer;
    }
    button:focus {
        outline: none;
    }
</style>

<body id="root"></body>


<script type="text/babel">

class StopWatch extends React.Component{
    state = {lapse: 0, running: false};
    handleRunClick = () => {
        this.setState(state => {
            if(state.running){
                clearInterval(this.timer);
            }else{
                const startTime = Date.now() - this.state.lapse;
                this.timer = setInterval(() => {
                    this.setState({
                        lapse: Date.now() - startTime,
                    })
                })
            }
            return {running: !state.running};
        })
    }

    handleClearClick = () => {
        storedValues.push("1");
        clearInterval(this.timer);
        this.setState({lapse: 0, running: false})
    }

    componentWillUnmounct(){
        clearInterval(this.timer);
    }

    render(){
        const {lapse, running} = this.state;
        return (
            <div className="mainDiv">
                <div className='title'>React Stopwatch</div>
                <label>{lapse}ms</label>
                <button onClick={this.handleRunClick}>{running ? '||' : '>'}</button>
                <button onClick={this.handleClearClick}>Clear</button>
            </div>
        )
    }
}

let storedValues = [];

const element = (
    <StopWatch />
)

ReactDOM.render(
    element,
    document.getElementById('root')
)

</script>