How to multiple the object state in array?

Question

Suppose I have an array:

const array = [
    {
        name: "Name 1",
        numbers: 3
    },
    {
        name: "Name 2",
        numbers: 2
    },
    {
        name: "Name 3",
        numbers: 3
    }
]

I want that every object with numbers value get multiplied by its state. Want this:

    // Expected Output
const array2 = [
    {
        name: "Name 1"
    },
    {
        name: "Name 1"
    },
    {
        name: "Name 1"
    },
    {
        name: "Name 2"
    },
    {
        name: "Name 2"
    },
    {
        name: "Name 3"
    },
    {
        name: "Name 3"
    },
    {
        name: "Name 3"
    }

]

Here every object is multiplied by its number value How can I do that?

Hint : you can loop through first array and create new array. — Devsi Odedra, May 20 '22 at 05:08
Why not? Loop to the value of numbers for each objects and add the same into the new array — Supritam, May 20 '22 at 05:12

Yosvel Quintero · Answer 1 · 2022-05-20T05:31:04.900

2

You can do:

const array = [{name: "Name 1",numbers: 3},{name: "Name 2",numbers: 2},{name: "Name 3",numbers: 3}]

const result = array.map(({ name, numbers }) => 
  [...Array(numbers)].map(_ => ({ name }))).flat()

console.log(result)

edited May 20 '22 at 05:31

answered May 20 '22 at 05:18

Yosvel Quintero

18,669
5
37
46

Rickard Elimää · Answer 2 · 2022-05-20T07:20:19.560

for (length of array) and while (something is not 0)

const array = [
    {
        name: "Name 1",
        numbers: 3
    },
    {
        name: "Name 2",
        numbers: 2
    },
    {
        name: "Name 3",
        numbers: 3
    }
]

function splitArray(arr) {
  let newArr = [], number = -1;
  
  for (let item of arr) {
    number = item.numbers;

    while (number--) {
      newArr.push(item.name);
    }
  }
  
  return newArr
}

console.log( splitArray(array) );

score 0 · Answer 3 · answered May 20 '22 at 05:16

Loop array item first and get the numbers and loop the numbers inside.

let newArray = [];
      for(i=0; i<array.length; i++){
        //get item number
        var numberCount = array[i].numbers;
        for(j=0; j<numberCount.length; j++){
            newArray.push(array[i].name);
        }
      }

score 0 · Answer 4 · answered May 20 '22 at 05:18

const array = [
  {
    name: "Name 1",
    numbers: 3
  },
  {
    name: "Name 2",
    numbers: 2
  },
  {
    name: "Name 3",
    numbers: 3
  }
]

const array2 = array.reduce(
  (previousValue, currentValue) => {
    for (let i = 0; i < currentValue.numbers; i++) {
      previousValue.push({ name: currentValue.name });
    }
    return previousValue
  },
  []
)

console.log(array2)

JuneC · Answer 5 · 2022-05-20T09:59:57.530

0

By using Js es6 .reduce() ~ MDN web docs

I think the readability is better than just .map().

const array = [{ name: "Name 1", numbers: 3 }, { name: "Name 2", numbers: 2 }, { name: "Name 3", numbers: 3 }]

const result = array.reduce((acc, { numbers, name }) => {
    [...Array(numbers)].forEach(o => acc.push({ name }))
    return acc
}, [])

console.log(result)

edited May 20 '22 at 09:59

answered May 20 '22 at 05:21

JuneC

59
7

score 0 · Answer 6 · answered May 20 '22 at 05:22

map() and for():

const array = [
    {
        name: "Name 1",
        numbers: 3
    },
    {
        name: "Name 2",
        numbers: 2
    },
    {
        name: "Name 3",
        numbers: 3
    }
]

const arr = array.map(el => {
  let elAr = []
  for(let i=0; i<el.numbers; i++){
    elAr = [...elAr, {name: el.name}]
  }
  return elAr
})
const result = arr.flat()
console.log(result)

How to multiple the object state in array?

6 Answers6