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())