Multidimensional objects in JavaScript

Not only arrays, but also objects can be multidimensional, here is an example:

javascriptlet obj = {
  a: {
    key1: 'a1',
    key2: 'a2',
    key3: 'a3',
  },
  b: {
    key1: 'b1',
    key2: 'b2',
    key3: 'b3',
  },
  c: {
    key1: 'c1',
    key2: 'c2',
    key3: 'c3',
  },
}

Let's display some elements of our object:

javascriptconsole.log(obj['a']['key1']); // shows 'a1'

You can also access elements as properties:

javascriptconsole.log(obj.a.key1); // shows 'a1'

You can combine both methods:

javascriptconsole.log(obj['a'].key1); // shows 'a1'
console.log(obj.a['key1']); // shows 'a1'

Задание 1

Given the following object:

javascriptlet obj = {
  key1: {
    key1: 1,
    key2: 2,
    key3: 3,
  },
  key2: {
    key1: 4,
    key2: 5,
    key3: 6,
  },
  key3: {
    key1: 7,
    key2: 8,
    key3: 9,
  },
}

Find the sum of the elements of this object.

Задание 2

Given the following object:

javascriptlet obj = {
  1: {
    1: 'a1',
    2: 'a2',
    3: 'a3',
  },
  2: {
    1: 'b1',
    2: 'b2',
    3: 'b3',
  },
  3: {
    1: 'c1',
    2: 'c2',
    3: 'c3',
  },
}

Display the element 'b2' and the element 'c1'.

Задание 3

Given the following object:

javascriptlet obj = {
  key1: {
    a: 1, b: 2, c: {
      d: 3,
      e: 4,
    }, f: 5,
  },
  key2: {
    g: 6, h: 7,
  },
}

Manually - without a loop, find the sum of all elements-numbers.