I am trying to e up with the way to loop through an array of values, save each value as a key and assign a 'true' boolean value for each key.

The goal is to create the following object:

{
  "arrayValue" : true,
  "anotherArrayValue" : true,
  "arrayValueAsWell" : true
}

I am doing:

  var objectToCreate = {};

  let myArray = ["arrayValue", "anotherArrayValue", "arrayValueAsWell"]
  let myArrayConverted = myArray.forEach((prop,index) => objectToCreate[prop] = true)

and getting:

  {
    0 : "arrayValue",
    1 : "anotherArrayValue",
    2 : "arrayValueAsWell"
  }

I am trying to e up with the way to loop through an array of values, save each value as a key and assign a 'true' boolean value for each key.

The goal is to create the following object:

{
  "arrayValue" : true,
  "anotherArrayValue" : true,
  "arrayValueAsWell" : true
}

I am doing:

  var objectToCreate = {};

  let myArray = ["arrayValue", "anotherArrayValue", "arrayValueAsWell"]
  let myArrayConverted = myArray.forEach((prop,index) => objectToCreate[prop] = true)

and getting:

  {
    0 : "arrayValue",
    1 : "anotherArrayValue",
    2 : "arrayValueAsWell"
  }

• javascript

• 1 objectToCreate[prop] = true; — there's no need to create a capital-B Boolean object. – Pointy Commented Apr 2, 2019 at 14:06
• @Pointy tried this way too, same result – a.tokayeva Commented Apr 2, 2019 at 14:08
• 2 Your edited code returns - > { arrayValue: true, anotherArrayValue: true, arrayValueAsWell: true} isn't that what you want ? – Mihai T Commented Apr 2, 2019 at 14:10
• 1 Why are you mixing var and let? – Emile Bergeron Commented Apr 2, 2019 at 14:12
• Just to note, myArrayConverted will be undefined. Array.prototype.forEach() returns undefined. – Jordan Stubblefield Commented Apr 2, 2019 at 14:16

4 Answers 4

You can use Array.prototype.reduce to create an object with the keys like this:

const myObject = ["arrayValue", "anotherArrayValue", "arrayValueAsWell"]
  .reduce((acc, value) => ({ ...acc, [value]: true }), {});

console.log(myObject);

The return value of forEach() is undefined. You also should assign the value to the object key with assignment (=) operator:

var objectToCreate = {};
let myArray = ["arrayValue", "anotherArrayValue", "arrayValueAsWell"];
myArray.forEach(prop => objectToCreate[prop] = true);
console.log(objectToCreate);

You could iterate the array and assign to the objectToCreate, like this:

  var objectToCreate = {};
  let myArray = ["arrayValue", "anotherArrayValue", "arrayValueAsWell"];
  myArray.forEach(key => objectToCreate[key] = true)';

You could map object and assign them all to one object with Object.assign

var array = ["arrayValue", "anotherArrayValue", "arrayValueAsWell"],
    object = Object.assign(...array.map(k => ({ [k]: true })));

console.log(object);