Convert two arrays to one object, with same key for each array in Javascript

Question

For example, I have two arrays like these.

const dateArray = ['January', 'February', 'March', 'April', 'May', 'June']

const InfoArray = [
  { Date : '2022-01', Active: 1 },
  { Date : '2022-02', Active: 12 },
  { Date : '2022-03', Active: 25 },
  { Date : '2022-04', Active: 33 },
  { Date : '2022-05', Active: 120 },
  { Date : '2022-06', Active: 335 },
]

However, I want combined these two arrays into an array of objects.

const result = [
  { month: 'January', Active: 1 },
  { month: 'February', Active: 12 },
  { month: 'March', Active: 25 },
  { month: 'April', Active: 33 },
  { month: 'May', Active: 120 },
  { month: 'June', Active: 335 },
]

I looked for some information, and did like

  const makeObjectWithTwoArray = () => {

    let chartObj = {}

    dateArray.forEach((element, index) => {
      chartObj[element] = infoArray[index]
    })

    return chartObj
  }

however doesn't work at all. (of course because each array can't have same keys with the code.)

Your help will be much appreciated.

You can do with .reduce or use lodash.unionBy. stackoverflow.com/a/39127782/6877699 — Marlom
– Marlom, Commented Jun 26, 2022 at 11:46
@Marlom it's just a .map() since the array lenght isn't changing. — pilchard
– pilchard, Commented Jun 26, 2022 at 11:48
use map and get the last number of Date and access the months array — cmgchess
– cmgchess, Commented Jun 26, 2022 at 11:49

Ele · Accepted Answer · 2022-06-26 11:49:58Z

3

You can use the function Array.prototype.map as follows:

const dateArray = ['January', 'February', 'March', 'April', 'May', 'June']
const InfoArray = [
  { Date : '2022-01', Active: 1 },
  { Date : '2022-02', Active: 12 },
  { Date : '2022-03', Active: 25 },
  { Date : '2022-04', Active: 33 },
  { Date : '2022-05', Active: 120 },
  { Date : '2022-06', Active: 335 },
];

const result = InfoArray.map(({Date, Active}) => {
  const [_, month] = Date.split("-");
  return {Active, month: dateArray[[Number(month) - 1]]};
});

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

answered Jun 26, 2022 at 11:49

Ele

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Mina · Accepted Answer · 2022-06-26 11:52:45Z

2

const dateArray = ['January', 'February', 'March', 'April', 'May', 'June']

const InfoArray = [
  { Date : '2022-01', Active: 1 },
  { Date : '2022-02', Active: 12 },
  { Date : '2022-03', Active: 25 },
  { Date : '2022-04', Active: 33 },
  { Date : '2022-05', Active: 120 },
  { Date : '2022-06', Active: 335 },
]


const result = InfoArray.map(item => {
  const monthNumber = item.Date.split('-')[1]
  const month = dateArray[+monthNumber - 1]
  return {
    Active: item.Active,
    month
  }
})


console.log(result)

answered Jun 26, 2022 at 11:52

Mina

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Comments

Alan Omar · Accepted Answer · 2022-06-26 12:00:09Z

2

You Actually don't need the dateArray you can just extract the month name from the Date property.

const InfoArray = [
  { Date : '2022-01', Active: 1 },
  { Date : '2022-02', Active: 12 },
  { Date : '2022-03', Active: 25 },
  { Date : '2022-04', Active: 33 },
  { Date : '2022-05', Active: 120 },
  { Date : '2022-06', Active: 335 },
]

let result = InfoArray.map(e => ({
  month: new Date(e.Date).toLocaleString('default', {month: 'long'}),
  Active: e.Active
}))

console.log(result)

answered Jun 26, 2022 at 12:00

Alan Omar

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1 Comment

Ele Over a year ago

Be careful because you can run into i18n issues.

Sinan Yaman · Accepted Answer · 2022-06-26 12:11:35Z

Another alternative is using .reduce.

Note: I didn't return [...arr, {...}] implicitly since it would have created a different array on each iteration. return arr is better if you are going to have a large data (potenitally)

const dateArray = ['January', 'February', 'March', 'April', 'May', 'June']

const InfoArray = [
  { Date : '2022-01', Active: 1 },
  { Date : '2022-02', Active: 12 },
  { Date : '2022-03', Active: 25 },
  { Date : '2022-04', Active: 33 },
  { Date : '2022-05', Active: 120 },
  { Date : '2022-06', Active: 335 },
]

const combined = InfoArray.reduce((arr, {Date, Active}) => {
  arr.push({
   Date: dateArray[Number(Date.split("-")[1]) -1],
   Active
  })
  return arr
}, [])

console.log("combined: ", combined)

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