Question

用js求出1到100的和

Answer 1

var sum = 0;
for(var i = 1; i <= 100; i++){
sum = sum + i;

}
alert(sum);

Answer 2

var num;
for(var i = 1 ; i <= 100 ; i++){
num += i ;
}

Answer 3

let go = num =>{
return num?num+go(num-1):0
}
go(100)