How do I create nested properties on object literals using bracket notation?

Question

The following works but I'm trying to find a way to omit the arrayOfObjects[1]['testParent'] = {} bit, imagine you wanted to add a value to an empty object that is nested 10 levels down, you would have to initialize each level with an empty {} first, I'm trying to find a workaround for that.

let arrayOfObjects = [
{},
{},
{},
]

arrayOfObjects[1]['testParent'] = {}
arrayOfObjects[1]['testParent']['testKey'] = 'testValue'

// is there a way to do the above in one line, without having to initialize testParent with an empty object on line 7?

console.log(arrayOfObjects)

arrayOfObjects[1]['testParent'] = {'testKey': 'testValue'}, like this? — user9090230
– user9090230, Commented Jun 16, 2018 at 19:56

mlibby · Accepted Answer · 2018-06-16 20:12:40Z

2

 arrayOfObjects[1] = {
    testParent: {
      testKey: 'testValue'
    }
 };

In fact, you can avoid the array indexer as well with something like:

 arrayOfObjects = [ 
    {},
    {
      testParent: {
        testKey: 'testValue'
      }
    },
    {}
 ];

edited Jun 16, 2018 at 20:12

answered Jun 16, 2018 at 19:57

mlibby

6,7941 gold badge35 silver badges42 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

lonesomeday Over a year ago

This is not JSON.

mlibby Over a year ago

@lonesomeday: because it is missing all the quotes, I suppose? I've removed the reference to JSON.

lonesomeday Over a year ago

No, because JSON is a format for data serialisation. This is just standard Javascript object syntax. Downvote removed, in any case.

Gallaxhar Over a year ago

This seems like the way to go for an arbitrary nesting, keeping it simple, etc. arrayOfObjects[1] = {testParent:{testParent:{testKey: 'testValue'}}}

Nenad Vracar · Accepted Answer · 2018-06-16 20:05:15Z

0

You can create custom method for this, using reduce that takes string and value and sets nested property.

let arr = [{}, {}, {}]

function set(obj, key, value) {
  key.split(".").reduce((r, e, i, a) => {
    return r[e] || (r[e] = a[i + 1] ? {} : value)
  }, obj);
}

set(arr, "0.testParent.testKey", "testValue")
set(arr, "2.a.b.f", "value")
set(arr, "2.a.b.c", "value")

console.log(arr)

answered Jun 16, 2018 at 20:05

Nenad Vracar

122k16 gold badges160 silver badges184 bronze badges

Comments

Jonas Wilms · Accepted Answer · 2018-06-16 20:06:51Z

0

Maybe a small helper can help you to omit the brackets:

const $ = (obj, key, ...keys) => key != undefined ? $(obj[key] || (obj[key] = {}), ...keys) : obj;

Usable as:

const arr = [];
$(arr, 1, "testParent").testKey = "testValue";

answered Jun 16, 2018 at 20:06

Jonas Wilms

139k20 gold badges164 silver badges164 bronze badges

Collectives™ on Stack Overflow

How do I create nested properties on object literals using bracket notation?

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

4 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related