javascript - 我试图在 JavaScript 中添加三个数字的总和，但它给了我 NaN。为什么？

Question

我想从用户那里收集三个数字并使用函数和循环添加它们。我不断想出 NaN。为什么是这样？我尝试将字符串提示转换为 Number 对象来解决此问题。

var userEntry1 = Number(window.prompt("Enter in a number of your choice"));
var userEntry2 = Number(window.prompt("Enter in a number of your choice"));
var userEntry3 = Number(window.prompt("Enter in a number of your choice"));
var sum;
var i;
function addNumb(userEntry1, userEntry2, userEntry3) {
    "use strict";
    sum = userEntry1 + userEntry2 + userEntry3;
    for (i = 1; i <= arguments.length; i += 1) {
        sum += Number(arguments[i]);

    }
    return sum;
    
}

addNumb(userEntry1, userEntry2, userEntry3);
window.console.log(sum);

Answer 1

在循环中，循环的长度等于 arguments 的长度，但由于它是一个基于 0 的数组，因此您的迭代次数太多了。更改<=至< :

var userEntry1 = Number(window.prompt("Enter in a number of your choice"));
var userEntry2 = Number(window.prompt("Enter in a number of your choice"));
var userEntry3 = Number(window.prompt("Enter in a number of your choice"));
var sum;
var i;

function addNumb(userEntry1, userEntry2, userEntry3) {
  "use strict";
  sum = userEntry1 + userEntry2 + userEntry3;
  for (i = 0; i < arguments.length; i += 1) {
    sum += Number(arguments[i]);

  }
  return sum;

}

addNumb(userEntry1, userEntry2, userEntry3);
window.console.log(sum);