Node.js: Reference an inner property of an object by a variable - node.js

Question

My Problem
Consider a nested object:
> { a: { b: { c: 3 } } }
{ a: { b: { c: 3 } } }
Accessing an inner property with a dot notation for fixed values is done using a dot notation:
> x.a.b.c
3
I would like to access an arbitrary property depending on some condition, for example, instead of accessing b I would like to access the property who's name is stored in the SOME_VARIABLE variable:
> x.a.{SOME_VARIABLE}.c
3
What have I tried
STFW. Probably don't know the exact terminology.
My question
How can I refer to an object property dynamically, with a property name defined in a variable?

Answer 1

There are multiple ways to access an object one of them being [] instead of dots if a object is var object = { inside : '1' } you can access it like this object['inside']. Remember to pass quotes inside if it's static and if it's dynamic pass the variable
I've added an example below
var a = { b: { c: 1 } };
var d = 'b';
console.log(a[d]['c']);

Answer 2

You might also consider using a library like lodash which provides functions to "reach inside" a complex object and return a value, of if the path doesn't exist, a default value.
Example:
const _ = require('lodash')
const target = {
foo: {
bar: {
baz: [1, 2, 3]
}
}
}
console.log(_.get(target, 'foo.bar.baz.1')) // ==> 2
console.log(_.get(target, 'foo.3.bar', 'DEFAULT')) // ==> DEFAULT
if (_.has(target, 'foo.bar')) {
// do something interesting
}
const newKey = 'blorg'
_.put(target, `foo.bar.${newKey}`, 'hello?')
/*
target is now {
foo: {
bar: {
baz: [1, 2, 3]
},
blorg: 'hello?'
}
}
*/