for循环在js里,貌似很重要,而且还挺让人晕头转向的…这个需要多练习了

<script type="text/javascript">
        // 1-100所有整数的和与平均值
        var he = 0;
        for (var i=0;i<=100;i++) {
            he = he + i;
        }
        console.log('1-100的整数和是:' + he);
        console.log('1-100的平均值为:' + he / 100);

        // 1-100所有偶数的和
        var he2 = 0;
        for (var shu = 1;shu <= 100;shu++) {
            if(shu % 2 != 0){
                continue;
            } else {
                he2 = he2 + shu;
            }
        }
        console.log('偶数的和为:' + he2);

        //使用while 1-100实现偶数的和
        var he4 = 0;
        var shu3 = 1;
        while ( shu3 <= 100) {
            shu3++;
            if (shu3 % 2 != 0) {
                continue;
            }
            he4 = he4 + shu3;
        }
        console.log('while实现的1-100偶数的和是:' + he4)
        // 100以内7的倍数的和
        var he3 = 0;
        for (var shu2 = 1;shu2 <= 100;shu2++) {
            if (shu2 % 7 ==0) {
                he3 = he3 + shu2;
            }
        }
        console.log('100以内7的倍数的和:' + he3);

        // 用☆打印一个矩形,要求5*5
        var str = '';
        for (var x = 1;x <=5 ; x++) {
            for (var y = 1;y <=5 ;y++) {
                str = str + '☆';
            }
            str = str + '\n';
        }
        console.log(str);

        // 使用☆用for循环打印一个三角形
        var str2 = '';
        for (var z = 1;z <= 10;z++) {
            for (var a = 1;a<=z;a++) {
                str2 = str2 + '☆';
            }
            str2 = str2 + '\n';
        }
        console.log(str2);

        // for循环完成99乘法表
        var str3 = '';
        for (var b = 1;b <= 9;b++) {
            for (var c = 1;c<=b;c++) {
                str3 = str3 +  c +  '×' + b + '=' + b * c + '\t';
            }
            str3 = str3 + '\n';
        }
        console.log(str3);

        //接收用户输入的用户名与密码,如果用户名与密码是:admin与123456,那么提示登陆成功,否则一直输入
        do {
            var user = prompt('用户名');
            var pwd = prompt('密码');
        } while (user !== 'admin' || pwd !== '123456')
        alert('登录成功');

        //计算1-100整数的累计和,但是跳过个位数为3的数字
        var he4 = 0;
        for (var d=1;d <= 100;d++){
            if (d % 10 ==3 || parseInt(d % 10 ==3)) {
                console.log('跳过:'+ d);
                continue;
            }
            he4 = he4 + d;
        }
        console.log('1-100除却个位数为3的数字的和是:' + he4);
		</script>