I want to return a JSON object from an array

Question

I have the following array.

numbers = ["1","2"]

I want to convert this array into the following object

numberList = {"1" : [], "2" : []}

I tried like following. but it does not work. I want to pass the number as a variable.

numbers.map( function(number) {
      return {number : []};
  })

JSON is a textual notation for data exchange. (More here.) If you're dealing with JavaScript source code, and not dealing with a string, you're not dealing with JSON. — T.J. Crowder
– T.J. Crowder, Commented Mar 18, 2021 at 18:17

Nina Scholz · Accepted Answer · 2021-03-18 18:18:55Z

5

You could map entries and build an object from it.

const
    numbers = ["1", "2"],
    object = Object.fromEntries(numbers.map(key => [key, []]));

console.log(object);

answered Mar 18, 2021 at 18:18

Nina Scholz

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Comments

silversunhunter · Accepted Answer · 2021-03-18 18:22:22Z

3

I think i would simply loop it and build the object

let numbers = ["1","2"];
let newObject = {};

for(let i=0; i < numbers.length; i++){
    newObject[numbers[i]] = [];
}

console.log(newObject);

The other answers here provide cleaner methods in my opinion. This is pretty old school.

answered Mar 18, 2021 at 18:18

silversunhunter

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Or even for (const number of numbers) { newObject[number] = []; } (And agreed on the loop. :-) Or fromEntries as Nina shows.)

I am realizing with all these answers there are cleaner ways to do this.

Oh, a simple loop is nice, clean, clear, and efficient IMHO. I certainly wouldn't use reduce. Overcomplicated and easy to get wrong.

epascarello · Accepted Answer · 2021-03-18 18:18:35Z

1

You want to take your array and convert it into an object. To do that you want to use reduce.

numbers = ["1","2"]

var result = numbers.reduce( function (o, n) {
  o[n] = [];
  return o;
}, {});

console.log(result);

answered Mar 18, 2021 at 18:18

epascarello

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