JavaScript之函数、数组作业

1.计算用户指定的数值内的奇数和，例如用户输入的是10，则计算1 + 3 + 5 + 7 + 9的和；

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function sumadd(n){
            let sum = 0;
            for (let i = 1; i <= n; i ++){
                if (i % 2 != 0){
                    sum += i;
                }
            } 
            return sum;
        }
        let userInput = prompt("请输入一个数字：");
        userInput = Number(userInput);
        console.log("奇数和为：" + sumadd(userInput));
    </script>
</body>
</html>

结果：

2.使用递归计算1 - 100的和

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function sum(n) {
            if (n <= 0){
                return 0;
            }else{
                return n + sum(n-1);
            }

        }
        console.log(sum(100))
    </script>
</body>
</html>

结果：