ReactJS 将我的奇怪数组转换为 object 以将其添加到列表中

Question

I have the following array:

[{…}]
0: {id: 2, createdAt: "2021-06-11T10:13:46.814Z", exchangedAt: "2021-06-11T08:04:11.415Z", imageUrl: "url", user: "user", …}
1: ....
2: ....
3: ....
....
length: 5
__proto__: Array(0)

I want to convert it to an object and I found this code, but all I receive is the 0:

Object.keys(fetchedData.data).map(key => console.log(key))

How to access and convert my 5 array values?

Answer 1

So I've iterated across your array and used the 'id' field as a key. The key for each object needs to be unique, so this assumes your ID is unique...

 const fetchedData = [ {id: 1, createdAt: "2021-06-11T10:13:46.814Z", exchangedAt: "2021-06-11T08:04:11.415Z", imageUrl: "url", user: "user"}, {id: 2, createdAt: "2021-06-11T10:13:46.814Z", exchangedAt: "2021-06-11T08:04:11.415Z", imageUrl: "url", user: "user"}, {id: 3, createdAt: "2021-06-11T10:13:46.814Z", exchangedAt: "2021-06-11T08:04:11.415Z", imageUrl: "url", user: "user"} ] obj = {} fetchedData.forEach(x => { tempX = {...x} delete tempX["id"] obj[x.id] = tempX }) console.log('Converted object', obj) //Using your method, just to log the values without converting it into an object, you could do... fetchedData.forEach(el => console.log("Individual Element", el))

...so when you use Object.keys() you are iterating across the keys of an object, but as this is an array of objects, the keys are just the indexes of the array. .forEach iterates across the array and gives you each element to work with.

You've used .map() in your code, which also iterates through an array, but returns a new array, so you could change each element. .forEach just iterates and doesn't return, so you're better off using this for logging to the console.

Answer 2

a = [
  {
     "id":1,
     "createdAt":"2021-06-11T10:13:46.814Z",
     "exchangedAt":"2021-06-11T08:04:11.415Z",
     "imageUrl":"url",
     "user":"user"
  },
  {
     "id":2,
     "createdAt":"2021-06-11T10:13:46.814Z",
     "exchangedAt":"2021-06-11T08:04:11.415Z",
     "imageUrl":"url",
     "user":"user"
  },
  {
     "id":3,
     "createdAt":"2021-06-11T10:13:46.814Z",
     "exchangedAt":"2021-06-11T08:04:11.415Z",
     "imageUrl":"url",
     "user":"user"
  },
  {
     "id":2,
     "createdAt":"2021-06-11T10:13:46.814Z",
     "exchangedAt":"2021-06-11T08:04:11.415Z",
     "imageUrl":"url",
     "user":"user"
  },
  {
     "id":4,
     "createdAt":"2021-06-11T10:13:46.814Z",
     "exchangedAt":"2021-06-11T08:04:11.415Z",
     "imageUrl":"url",
     "user":"user"
  }
]
(5) [{…}, {…}, {…}, {…}, {…}]
Object.keys(a).map(key => console.log(key))
VM532:1 0
VM532:1 1
VM532:1 2
VM532:1 3
VM532:1 4

It is accessing to 5 values.