长阵列的对象解构解决方案？ [英] Object destructuring solution for long arrays?

问题描述

查看以下代码：

let lecture = {
    id: 2,
    title: "MyTitle",
    topics: [
    {
        title: "John",
        age: 1
    },
    {
        title: "John2",
        age: 2
    },
    {
        title: "John3",
        age: 3
    }]
}

我想提取主要的标题属性和数组中的第三个年龄（通过对象解构）

I want to extract the main title property and the third age in the array (via object destructuring)

我可以通过 来实现：

let { title:lectureTitle , topics:[,,{age:thirdAge}]} = lecture;
console.log(lectureTitle,thirdAge);//MyTitle 3

问题

Question

但是，如果数组有100个项目，而且我想要第99个年龄？

But what if the array has 100 items and I want the 99'th age ?

我该怎么办？对象解构提供了一个解决方案吗？

How would then I do it ? Does object destructuring offer a solution for that?

推荐答案

但是，如果数组有100项，我想要99岁？

But what if the array has 100 items and I want the 99'th age ?

数组是对象，所以这样做：

Arrays are objects, so this will do:

let {title: lectureTitle, topics: {98: {age: thirdAge}}} = lecture;

---

注意 [...] 解构类型可以使用任何可迭代的方式，而 {...} 仅适用于对象（因此阵列）。所以上面的解决方案不适用于任意迭代（并且这个AFAIK没有一般的解决方案）。

---

Note however that the [...] type of destructuring works with any iterable, whereas {...} only works with objects (and therefore arrays). So the solution above wouldn't work with arbitrary iterables (and there is no general solution for this AFAIK).

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