arr.findIndex() returns -1

Question

恐怕这应该是显而易见的，因为我的事情是基于普通的 Vanille JS。无论如何，出于任何原因我无法解决我的问题。谁能帮帮我？

我在 reducer 中的代码快照：

> case TOGGLE_PRODUCT:
>       const newProducts = [...state.allProducts];
>       console.log("All products: ", newProducts);
>       console.log("Passed product: ", action.productId);
>       console.log("Should have found: ", newProducts[1]);
>       const toggledProduct = newProducts.findIndex(
>         (el) => el.id === action.productId
>       );
>       console.log("Found: ", toggledProduct);

控制台输出：

All products:  Array [
  Product {
    "amount": 0,
    "department": "Molkereiprodukte",
    "id": "id1",
    "product": "Milch 3,5%",
    "status": false,
  },
  Product {
    "amount": 0,
    "department": "Molkereiprodukte",
    "id": "id2",
    "product": "Yoghurt",
    "status": false,
  },
  Product {
    "amount": 0,
    "department": "Ceralien",
    "id": "id3",
    "product": "Müsli",
    "status": false,
  },
]
Passed product:  Object {
  "id": "id2",
}
Should have found:  Product {
  "amount": 0,
  "department": "Molkereiprodukte",
  "id": "id2",
  "product": "Yoghurt",
  "status": false,
}
Found:  -1

为什么 find() 方法没有 return 结果？？？

提前致谢！

Answer 1

你的 action.productId 是 object 不是 string

  const toggledProduct = newProducts.findIndex(
    (el) => el.id === action.productId.id /** <--here */
  );

Answer 2

findIndex用于查找需要Array.find获取元素数据的元素的desire index。你得到 -1 的原因是因为 action.productId 是一个对象。您需要比较 action.productId.id


const toggledProduct = newProducts.find(el => el.id === action.productId.id );

arr.findIndex() returns -1

arr.findIndex() returns -1

arrays

find

redux

react-redux