通过比较两个 Arrays 获取值

Question

I have two array one is the state like this

const [state,setState] = useState([])

and the another one is am getting from a form when it is submitted;

   ids = [4,5,6]
setState(ids)

Now, when i update the state second time the values are there ie 4,5,6 in the state. so the values are getting duplicated ie 4,5,6,4,5,6

What i want is to make sure that only the elements which is not present in the array gets pushed not all,and i get the valid output like following.

4,5,6,7

If 7 is added.

What i did is like this, which is totally wrong

 const filterss = [...state];
      setState([]);
      filterss.push(values);
      setState(filterss);

Answer 1

  const filters = [...state];
  values.forEach(item => {
    if (filters.indexOf(item) < 0) {
      filters.push(item);
    }
  })
  setState(filters);

Answer 2

 const ids=[4,5,6] let formSubmitIds=[4,5,6,7] let uniquieIds=[...new Set([...ids,...formSubmitIds])] console.log(uniquieIds)

Simply use this logic to setState accordingly ie setState(uniquieIds)

ids are the stored values in state

formSubmitIds is the new array which you are getting on submit of form

[...ids,...formSubmitIds] will merge both arrays

Set is used to remove duplicates

[......new Set] will convert Set back to an array with unique ids only

Answer 3

First push all the old and new values in a single array then try using Set() to get unique values in the array. Here's the code.

setState(new Set(arrayName)) 

Answer 4

Use Set() constructor to achieve your goal.

Try:

const [state, setState] = useState([])

const ids = [4,5,6]
const formSubmittedIds = [4,5,6,7]

setState([...new Set([...ids, ...formSubmittedIds])]) // Sets [4, 5, 6, 7] to the state

Happy coding:)