如何有条件地破坏物体？

Question

我有以下破坏：

const {
    user: {
        username,
        image,
        uid
    } = {},
    gallery: {
        image: picture,
    } = {},
} = data

问题是gallery有时是null（不是picture中的gallery），即使我需要的是picture中的gallery存在。换句话说，gallery: null，而不是gallery.image: null。

因此，我得到：

null不是对象

gallery.image的错误消息。

我如何有条件地进行解构，以便在存在gallery.image时使用它，但在空时gallery不被解构？

Answer 1

Fallbacks仅适用于值为undefined，但不适用于null

• 这将起作用：

const data = {
  user: {
    username: 'Alice',
    image: 'alice.png',
    uid: 1
  },
  gallery: undefined
};

const {
    user: {
        username,
        image,
        uid
    } = {},
    gallery: {
        image: picture,
    } = {},
} = data;

console.log(username, image, uid, picture);

• 但是这不会：

const data = {
  user: {
    username: 'Alice',
    image: 'alice.png',
    uid: 1
  },
  gallery: null
};

const {
    user: {
        username,
        image,
        uid
    } = {},
    gallery: {
        image: picture,
    } = {},
} = data;

console.log(username, image, uid, picture);

---

因此，您可以像这样破坏它之前手动创建一个从null到{}的后备：

const data = {
  user: {
    username: 'Alice',
    image: 'alice.png',
    uid: 1
  },
  gallery: null
};

const {
    user: {
        username,
        image,
        uid
    } = {},
    gallery: {
      image: picture,
    }
} = {...data, gallery: data.gallery || {}};

console.log(username, image, uid, picture);