I have an array like ['animals', 'cats', 'cute', 'fast', 'small', ...], and want to access nested keys of the object like

let object = {
  one: {
    two: {
      three: {
        // and so on
      }
    }
  }
}

Usually I would write object['animals']['cats']['cute']['fast']['small']..

The problem is that keys and the number of levels are dynamic (so I can get objects with 2 nested levels or 50), so I have no idea how it can be done

Thanks in advance for any help

I have an array like ['animals', 'cats', 'cute', 'fast', 'small', ...], and want to access nested keys of the object like

let object = {
  one: {
    two: {
      three: {
        // and so on
      }
    }
  }
}

Usually I would write object['animals']['cats']['cute']['fast']['small']..

The problem is that keys and the number of levels are dynamic (so I can get objects with 2 nested levels or 50), so I have no idea how it can be done

Thanks in advance for any help

• javascript
• arrays
• object
• nested
• nested-documents

• which part is known, the key you want to extract from the object, or the structure of the object itself? – Michael Rodriguez Commented Jan 17, 2020 at 23:13
• @MichaelRodriguez while writing code - nothing, while script running - everything (how many levels, what key on each level and of course I have access to the object) – Max Mikhalchuk Commented Jan 17, 2020 at 23:17

1 Answer 1

Iterate over the array of keys with .reduce, where the accumulator is the current nested object:

let object = {
  one: {
    two: {
      three: {
        prop: 'val'
      }
    }
  }
};

const props = ['one', 'two', 'three', 'prop'];
const nestedVal = props.reduce((a, prop) => a[prop], object);
console.log(nestedVal);

To assign a value at the same point, first pop off the last key, use the same reduce trick to get to the last object, and assign to the property at the last key with bracket notation:

let object = {
  one: {
    two: {
      three: {
        prop: 'val'
      }
    }
  }
};

const props = ['one', 'two', 'three', 'prop'];
const lastKey = props.pop();
const nestedObj = props.reduce((a, prop) => a[prop], object);
nestedObj[lastKey] = 'newVal';
console.log(object);