React Javascript, creating new arrays from existing

Question

I have a array and I need to create new array based on existing.



function CartDetails() {


  const items = [ {"id": 14,'name' :'d'},{ "id": 15,'name' :'c'}]  // FROM THIS ARRAY I NEED TO COPY

 let newarray= [] // RESULTANT ARRAY

useEffect(()=>{

    for (let i in items){ quantity.push(i.id:1)} // MY METHOD OF ARRAY COPY but it is wrong
        },[])

    return (</>)


export default CartDetails

I want to copy the id from parent array and add to new array,

expected result newarray = [{ 14:1},{ 15:1}], here 14 and 15 are parent array ID's and 1 is constant

DSCH · Accepted Answer · 2020-05-28 09:57:28Z

3

You can try:

const items = [ {"id": 14,'name' :'d'},{ "id": 15,'name' :'c'}]
const newArray = items.map(item => ({[item.id]:1}));
console.log(newArray);

answered May 28, 2020 at 9:57

DSCH

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2 Comments

Anoop K George Over a year ago

Thanks, How do {item.id} method gets wrong ? and [item.id] is the correct way

DSCH Over a year ago

Since you want to create an object item, you have to use the curly braces. Then assign the ID as the key - i.e. to the left of the colon and the value to its right. I used square brackets on the left hand side as the key is dynamic - meaning each iteration will provide a different key and it's not hard coded. ({age: 20} vs {[currentProperty]: some value})

Anh Tuan · Accepted Answer · 2020-05-28 09:56:28Z

1

const newArr = items.map(item => {
      return {
       [item.id] : 1
      }
    })

check this out

answered May 28, 2020 at 9:56

Anh Tuan

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2 Comments

qristjan Over a year ago

var newItems = [...items].map(i => ({[i.id]: 1}))

Anh Tuan Over a year ago

why you need [...items] . basicly, map not modify your own array (items)

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