前端学习——jsDay4

news2025/2/22 14:30:47

函数

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函数使用

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小练习

<!DOCTYPE html>
<html lang="zh-CN">
<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>
      function hi(){
        document.write(`hi~`)
      }
      hi()
    </script>
</body>
</html>

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函数传参

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小练习

<!DOCTYPE html>
<html lang="zh-CN">
<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>
      function getsum(num1, num2){
        document.write(num1 + num2)
      }
      getsum(10,30)
    </script>
</body>
</html>

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小练习

<!DOCTYPE html>
<html lang="zh-CN">

<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>

        let arr = [90, 85, 93, 100, 50, 60]
        function getsum(arr) {
            let sum = 0
            for (let i = 0; i < arr.length; i++) {
                sum += arr[i]
            }
            document.write(sum)
        }
        getsum(arr)
    </script>
</body>

</html>

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函数返回值

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小练习

<!DOCTYPE html>
<html lang="zh-CN">

<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>
        function getmax(x, y) {
            if (y > x)
                return y
            else
                return x
        }
        document.write(getmax(5, 10))
    </script>
</body>

</html>

<!DOCTYPE html>
<html lang="zh-CN">

<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>
        function getmax(arr = []) {
            let max = 0
            for (let i = 0; i < arr.length; i++) {
                if (arr[i] > max)
                    max = arr[i]
            }
            return max
        }
        document.write(getmax([5, 10, 50, 60]))
    </script>
</body>

</html>

<!DOCTYPE html>
<html lang="zh-CN">

<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>
        function getmax(arr = []) {
            let max = arr[0]
            let min = arr[0]
            for (let i = 0; i < arr.length; i++) {
                if (arr[i] > max)
                    max = arr[i]
                if (arr[i] < min)
                    min = arr[i]
            }
            return [max, min]
        }
        document.write(getmax([5, 10, 50, 60]))
    </script>
</body>

</html>

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作用域

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a=4,b=22

匿名函数

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综合案例

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<!DOCTYPE html>
<html lang="zh-CN">

<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>
        let input = prompt('请输入总秒数：')
        function bu0(a)
        {
            if(a<10)
                a='0'+a
            return a
        }
        function change(input)
        {
            let h=parseInt(input/60/60%24)
            let m=parseInt(input/60%60)
            let s=parseInt(input%60)
            h=bu0(h)
            m=bu0(m)
            s=bu0(s)
            console.log(`${input}秒转化：${h}小时${m}分钟${s}秒`)
        }
        change(input)
    </script>
</body>

</html>