在另一个对象数组 JavaScript 中遍历一个对象数组 [关闭]答案

【问题标题】：Iterate through an Array of Objects within another Array of Objects JavaScript [closed]在另一个对象数组 JavaScript 中遍历一个对象数组 [关闭]
【发布时间】：2023-02-20 23:59:42
【问题描述】：

我创建了一个对象数组。在这个对象数组中，还有另一个对象数组。

let firstArray = [
    {element: "This is a string"},
    {element: "This is a string"},
    {element: "This is a string"},
    {element: "This is a string"},
    {
        element: "This is a string",
        secondArray: [
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                 ]
                     
    },
];

我想遍历名为“secondArray”的数组中的所有对象。然后程序应将所有“userRating”元素加在一起并将答案记录到控制台。

我试过的代码不能正常工作：

for (let i of firstArray){
    console.log(element);
    for (let j of firstArray.secondArray) {
        console.log(j.userRating);
    }
}

【问题讨论】：

你有没有尝试过？如果是这样，你能和我们分享一下吗？
“我想要”不是问句。请向我们展示您尝试过的方法，并解释具体的问题所在。

标签： javascript arrays object iteration

【解决方案1】：

您可以结合使用 forEach 方法和 reduce 方法来遍历 secondArray 中的对象，将所有 userRating 元素相加，然后将答案记录到控制台。这是一个例子：

let firstArray = [
    {element: "This is a string"},
    {element: "This is a string"},
    {element: "This is a string"},
    {element: "This is a string"},
    {
        element: "This is a string,
        secondArray: [
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                     {
                         otherElements: "This is a different element"
                         userRating: 5
                     },
                 ]
                     
    },
];
let secondArray = firstArray.find(obj => obj.secondArray)?.secondArray || []; // to find the secondArray in firstArray and handle it not being present

let totalRating = secondArray.reduce((total, obj) => {
  return total + obj.userRating;
}, 0);

console.log(totalRating);

此代码将首先使用 find 方法在 firstArray 中找到 secondArray。如果它不存在，它将默认为一个空数组。然后，它将使用 reduce 方法将 secondArray 中的所有 userRating 值相加。最后，它将总评分记录到控制台。

【讨论】：