js练习题

<script>
        var sum = 0
        for (i = 1; i <= 100; i++) {
            if (i % 3 == 0 && i % 7 == 0) {
                sum = sum + i
            }
        }
        document.write(sum)
    </script>

 <script>
        var str = ''
        for (var i = 1; i <= 5; i++){
            for(j =1; j<i+1; j++){
                str +='☆'
            }
            str+='\n'
        }
        console.log(str);
    </script>

 <script>
        var admin = 'admin';
        var password = '......';
        var uname = prompt('请输入您的用户名')
        var upassword = prompt('请输入您的密码')
        while (uname != admin || upassword != password) {
            alert('您的用户名和密码错误,请重新输入')
            uname = prompt('请输入您的用户名')
            upassword = prompt('请输入您的密码')
        }
        alert('恭喜您登录成功！')
    </script>

<script>
        /* 求1-100之间个位数不为3的数的累加和。 */
        var sum = 0;
        for(var i = 1 ; i<=100; i++){
            if((i%10)==3){
                continue;
            }
            sum +=1;
        }
        console.log(sum);//90
    </script>

 <script>
        /* 简易ATM */
        var money = 0
        while (true) {
            var str = +prompt(`
            请输入您要的操作
            1.存钱
            2.取钱
            3.显示余额
            4.退出
            `)
            switch (str) {
                case 1:
                    var cun = +prompt('请您输入存钱的金额:')
                    money += cun
                    break
                case 2:
                    var qu = +prompt('请您输入取钱的金额:')
                    money -= qu
                    break
                case 3:
                    alert(`您卡上的余额是${money}元`)
                    break
                case 4:
                    alert(`退出成功`)
            }
            if (str == 4) {
                break
            }
        }
    </script>

1. function getMax(a, b) {
2. return a > b ? a : b
3.         }
4. console.log(getMax(99, 4));

 function getMax(a, b, c) {
            var temp = a > b ? a : b
            return temp > c ? temp : c
        }
        console.log(getMax(2, 1, 4));

function getResult(n) {
            var flag = true//假设这个数就是质数
            for (var i = 2; i < n; i++) {
                if (n % i == 0) {
                    flag == false
                    break
                }
            }
        }

  var arr = [1, 2, 3, 4, 5, 6, 7]
        var newArr = []
        function fn(arr) {
            for (var i = 0; i < arr.length; i++) {
                newArr[newArr.length] = arr[arr.length - i - 1]
            }
            return newArr
        }
        var res = fn(arr)
        console.log(res);