How to append array values in an object as property and value?

Question

Go through the array numbers and put each number (2, 4, 5, 37, 0) as a property of the object numbers_duplicates. The value of each property should be that number multiplied by two. (first create the empty object before starting to add the properties and values).

var numbers= [2, 4, 5, 37, 0]
var duplicate_numbers = {}

// later it should be like this { 0: 0, 2: 4, 4: 8, 5: 10, 37: 74}

enter code here for (var i = 0; i < numbers.length; ++i) {
duplicate_numbers.push( numbers[i]*2 );
    duplicate_numbers.push( i );}

How do I solve this problem?

Possible duplicate of How to count duplicate value in an array in javascript — Hamit YILDIRIM
– Hamit YILDIRIM, Commented May 19, 2019 at 21:24

Aleksandar Hristov · Accepted Answer · 2019-05-19 21:12:12Z

2

Here you go mate!

    let arr = [2, 4, 5, 37, 0];
    let obj = {};

    arr.forEach((x) => {
       obj[x] = x*2
    });
    
    console.log(obj);

answered May 19, 2019 at 21:12

Aleksandar Hristov

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Comments

Shidersz · Accepted Answer · 2019-05-19 21:23:27Z

For get or set an object property, you can use bracket notation. Here is a version using the basic for loop you have written.

var numbers = [2, 4, 5, 37, 0];
var duplicate_numbers = {};

for (var i = 0; i < numbers.length; i++)
{
    duplicate_numbers[numbers[i]] = numbers[i] * 2;
}

console.log(duplicate_numbers);

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

Alternatively, you can also use Array.reduce() in this way:

var numbers = [2, 4, 5, 37, 0];

var duplicate_numbers = numbers.reduce((acc, n) => (acc[n] = 2 * n, acc), {});

console.log(duplicate_numbers);

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

Ramon Portela · Accepted Answer · 2019-05-19 21:13:01Z

0

You need to use a Object to do this, a object is made of key, value pairs.

const numbers_duplicates = {};
const numbers =  [2, 4, 5, 37, 0];

numbers.forEach(number => { numbers_duplicates[number] = number * 2 });

answered May 19, 2019 at 21:13

Ramon Portela

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Comments

Karel · Accepted Answer · 2019-05-19 21:26:16Z

0

const numbers = [2, 4, 5, 37, 0] ;
const duplicateNumbers = {};
const numbersSorted = numbers.sort((a, b) => a - b);

for (let i = 0; i < numbersSorted.length; i++) {
  duplicateNumbers[numbersSorted[i]] = numbersSorted[i] * 2;
}

answered May 19, 2019 at 21:26

Karel

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Comments

Rabov · Accepted Answer · 2019-05-19 22:15:25Z

0

You may want to consider a Map. This is a special object exactly made for purposes that you need. It has a bunch of arraylike methods for handling that kind of objects. Please take a look Map.

var numbers= [2, 4, 5, 37, 0];
var duplicate_numbers = new Map();
numbers.forEach((val)=> {
    duplicate_numbers.set(val, val*2);
})

answered May 19, 2019 at 22:15

Rabov

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Comments

Murtaza Hussain · Accepted Answer · 2019-05-19 21:37:27Z

-1

var numbers = [2, 4, 5, 37, 0];
var duplicate_numbers = {};

var result = numbers.forEach(num => {
  duplicate_numbers[num] = num * 2
});

console.log(duplicate_numbers);

edited May 19, 2019 at 21:37

answered May 19, 2019 at 21:12

Murtaza Hussain

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4 Comments

Andy Over a year ago

map will always return a new array. The OP wants an object.

Murtaza Hussain Over a year ago

updated the answer, please check now.. i miss understood the question

Banzay Over a year ago

What if num is zero?

Murtaza Hussain Over a year ago

I think my answer is perfectly working accordin to the question, not sure why it's marked negative

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