switch,for循环语句的使用

//while循环：先判断条件，再执行循环
/*    var sum = 0;
    var i = 1;
    while(i <= 10 )
    {
        alert("刚进循环时候："+ sum +","+i);
        sum = sum + i;
        i++;
        alert("循环执行之后："+ sum +","+i);
    }
    alert(sum);*/
    
    // do-while循环：循环体内的代码，至少执行一次
/*    var sum1 = 0;
    var j    = 1;
    do
    {
        sum1 =sum1 + j;
        j++;
    }while (j <= 10);
    alert(sum1);*/
    
    //for 循环
/*    var sum2 = 0;
    var biao = 0;
    for (var i = 0; i <= 10;i++) {
        sum2 = sum2 + i;
        biao++;//语句执行的次数
        
    }
    alert(biao);*/