为什么在尝试破坏对象时得到 "Destructuring expressions can only have identifier references"？

Question

我有以下对象:

const john = {
  family: [
    { firstName: 'david', secondName: 'jana' },
    { firstName: 'eyal', secondName: 'shani ' },
  ],
};

我想在一次操作中得到 'david' 字符串。所以我尝试了以下代码：

const { family:[0]{firstName}}} = john;

但我收到错误消息：

"Destructuring expressions can only have identifier references"

谁能用简单的语言告诉我（因为我是这门语言的新手）我做错了什么？

Answer 1

要通过解构提取深度嵌套的值，语法几乎与 声明具有这些属性的对象 相同。 family:[0] 不是有效语法 - 相反，您需要用数组定界符将 family 的内容括起来：

const john = {
  family: [{
      firstName: 'david',
      secondName: 'jana'
    },
    {
      firstName: 'eyal',
      secondName: 'shani '
    },
  ],
};

const { family:[{firstName}]} = john;

console.log(firstName);

但我强烈建议不要使用这样的嵌套解构。写作、阅读和理解是如此困难。至少对外部访问最好使用纯点符号，例如

const john = {
  family: [{
      firstName: 'david',
      secondName: 'jana'
    },
    {
      firstName: 'eyal',
      secondName: 'shani '
    },
  ],
};

const { firstName } = john.family[0];
console.log(firstName);

为什么在尝试破坏对象时得到 "Destructuring expressions can only have identifier references"？

Why getting "Destructuring expressions can only have identifier references" when trying to destruct an object?

javascript

json

object

destructuring