求1-100数字的和

function sum_all(){
    var result = 0;
    for(var i=0;i<=100;i++){
        result=result+i;
    }
    return result;
}
var s = sum_all(100);
console.log(s);

// while循环
function sum_all(){
    var result= 0;
    var i=0;
    while(i<=100){
        i++;
        result=result+i;
    }
    return result;
}
//do while语句
function sum_all(){
    var result = 0;
    var i=0;
    do{
        i++;
        result=result+i;
    }
    while(i<=100){
        return result
    }
}
alert(sum_all())