Create a dynamic number of object keys with "true" values in Javascript

November 28, 2022

I want to create an object with every value as "true" and the length of keys will be same with array length.

Example :

const myCar = [{name:ford,type:A},{name:opel,type:B}]

The output want to be like this below

{0:true,1:true}

If the length from the array myCar will be 3 so the output will be like this as well:

{0:true,1:true,2:true}

>Solution :

You can reduce to get a counter and an object

const myCar = [{ name: 'ford', type: 'A' }, { name: 'opel', type: 'B' }];

const myObj = myCar.reduce((acc,_,i) => (acc[i] = true,acc),{});

console.log(myObj);

Breakdown

const myObj = myCar
  .reduce(
    (acc,_,i) => // reduce passes the accumulator, the current object which we ignore here and the index
      (acc[i] = true // set the accumulator at key=index to true 
         ,acc)   // and use the comma operator to return the accumulator
     ,{});       // initialise the accumulator to an empty object