handWritingJS/setInterval.html at master · ShuchenEason/handWritingJS · GitHub

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<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        // Method1
        let timeMap = {}
        let id = 0
        function mySetInterval(foo, timeout) {
            let timeID = id
            id++
            const fn = () => {
                foo()
                timeMap[timeID] = setTimeout(() => { fn() }, timeout)
            }
            timeMap[timeID] = setTimeout(fn, timeout)
            return timeID
        }
        function myClearTimeout(timeID) {
            clearTimeout(timeMap[timeID])
            delete timeMap[timeID]
        }

        // Method2
        // function mySetInterval(foo, timeout) {
        //     var timer = {
        //         id: null
        //     }

        //     function fn() {
        //         foo();
        //         timer.id = setTimeout( ()=> {
        //             fn();
        //         }, timeout);
        //     }
        //     fn();
        //     return timer
        // }

        // function myClearTimeout(timer) {
        //     clearTimeout(timer.id);
        // }


        const newTime = mySetInterval(() => { // 此处id是Number类型，是值的拷贝而不是引用
            console.log(new Date())
        }, 1000)

        setTimeout(() => { // 2秒后清除定时器
            myClearTimeout(newTime)
        }, 5000)

    </script>
</body>

</html>