javascript - 在 JavaScript 中添加数组

Question

如何使用循环将数组的总和加在一起，并且它只会输出数组的总和？

function exercise07Part1() {
    //declare variables
    const MAXIMUM_NUMBER = 10;
    var someNumbers;
    var sumOfNumbers;
    var output;
    var counter;

    //assign 10 variables to the array
    someNumbers = [12,67,90,34,32,67,29,74,49,22];

    //assign variable to counter for the loop
    counter = 1;
    sumOfNumbers = 0;

    while (counter <= someNumbers.length) {
        sumOfNumbers += someNumbers[counter];
        counter++;
    }

    output = document.getElementById('outputPart1');
    output.innerHTML = "Array: [" + someNumbers + "]<br />Sum: " + sumOfNumbers;
}

Answer 1

它正在返回NaN因为您要超出数组范围并添加值 undefined至sumOfNumbers 。数组中的最后一个元素比其长度小 1，这意味着您的 while循环条件应该是 counter < someNumbers.length而不是counter <= someNumbers.length 。在最后一次迭代中，您访问的是 undefined值，这导致总和变为 NaN当您添加它时。

此外，数组的索引是从零开始的，这意味着 counter需要从 0 开始而不是1 (您正在跳过数组中的第一个值)。

var someNumbers = [12, 67, 90, 34, 32, 67, 29, 74, 49, 22];
var sumOfNumbers = 0;

// Start at '0' rather than '1'
var counter = 0;

while (counter < someNumbers.length) {
    sumOfNumbers += someNumbers[counter];
    counter++;
}

console.log(sumOfNumbers); // 476