整数の検証と和までのjs

Question

var a = prompt("Please write an integer number greater than 0"); 
while ((a <= 0) || (Math.round(a) != a)) { 
    alert("Number that you have wrote is wrong, please write another one."); 
    var a = prompt("Please write an integer number greater than 0"); 
}; 
var i; 
var sum; 
for (i = 0; i <= a; i++){ 
    var s = sum += i; 
}; 
    document.write("your sum till your number is = " + s); 

私は0より大きい整数を書いて、その後に画面に書き込むようにしましたが、その数まで加算しますが、答えに何か問題がありますあなたの番号が= NaN >>になるまで、その合計は< <です。 誰かがそのエラーで私を助けることができますか？前もって感謝します。

Answer 1

1. 実行し、あなたのループでvar sum = 0;

2. を宣言sum += i;

例：

var a = prompt("Please write an integer number greater than 0"); 
 

 
while ((a <= 0) || (Math.round(a) != a)) { 
 
    alert("Number that you have wrote is wrong, please write another one."); 
 
    var a = prompt("Please write an integer number greater than 0"); 
 
} 
 

 
var i; 
 
var sum = 0; 
 

 
for (i = 0; i <= a; i++){ 
 
    sum += i; 
 
}; 
 
    document.write("your sum till your number is = " + sum);