将数组分解为对象 [英] Destructuring array into an object

问题描述

我正在尝试用javascript进行数组解构并遇到一些令人费解的行为

I am trying to do array destructuring in javascript and encounter some very puzzling behavior

这是我的代码-

 let res = {
            start: {},
            end: {},
        };
[res.start.hour, res.start.minute] = [7, 20]
[res.end.hour, res.end.minute] = [17, 30]
console.log(res)

输出为

{ start: { hour: 17, minute: 30 }, end: {} }

由于某种原因，[17，30]被分配给res.start，而不是res.end.

For some reason, [17, 30] were assigned to res.start, instead of res.end.

此外，如果我添加如下的console.log语句

Furthermore, if I add a console.log statement like below

 let res = {
            start: {},
            end: {},
        };
[res.start.hour, res.start.minute] = [7, 20]
console.log(JSON.stringify(res));
[res.end.hour, res.end.minute] = [17, 30]
console.log(res)

然后它起作用.res.end将获得正确的值.输出-

Then it works. res.end would get the correct value. Output --

{"start":{"hour":7,"minute":20},"end":{}}
{ start: { hour: 7, minute: 20 },
  end: { hour: 17, minute: 30 } }

我进行了搜索，并阅读了有关MDN的MDN页面，但找不到对此的解释.提前感谢您的帮助.

I've searched, and read thru MDN page on destructure, but couldn't find an explanation to this. Appreciate your help in advance.

推荐答案

尝试一下:

let res = {
  start: {},
  end: {}
};
[res.start.hour, res.start.minute] = [7, 20]; // Notice the semicolons.
[res.end.hour, res.end.minute] = [17, 30];
console.log(res);

我将您的代码从第一块复制粘贴到VS Code中，并使用了"Alt + Shift + F"(自动格式化).它将代码固定为以下代码，表明明显有问题:

I copy-pasted your code from the first block into VS Code and used 'Alt + Shift + F' (auto-formatting). It fixed the code to the following, indicating that something is clearly off:

let res = {
  start: {},
  end: {}
};
[res.start.hour, res.start.minute] = [7, 20][(res.end.hour, res.end.minute)] = [
  17,
  30
];
console.log(res);

事实证明，分号有时在JavaScript中确实很重要.

As it turns out, semicolons do matter sometimes in JavaScript.

这篇关于将数组分解为对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！