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) 

Answer 1

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

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

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

Answer 2

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.abf", "value") set(arr, "2.abc", "value") console.log(arr) 

Answer 3

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";