How to access property of nested object given dynamic keys?

Question

I have a nested object of which I do not know the structure of. For example:

const nestedObject = {
  "one": {
    "two": {
       "three": 3
     }
  }
}

I wanted to display value of three.

I have an array like this so that I know how to navigate the object in order to get to three:

const keys = ["one", "two", "three"]

This doesn't have to be structured this way.

So how do I access one.two.three given the keys array above? Or some other data structure. I was thinking of doing a recursion, but it seems too complex and I feel like there is a simple solution out there.

Please post the JavaScript in a [mcve]. If you haven't actually tried anything yet...do so. — zer00ne, Apr 15 '19 at 09:21
Possible duplicate of [Convert JavaScript string in dot notation into an object reference](https://stackoverflow.com/questions/6393943/convert-javascript-string-in-dot-notation-into-an-object-reference) — Kévin Bibollet, Apr 15 '19 at 09:23

score 11 · Accepted Answer · answered Apr 15 '19 at 09:22

11

You can do it with a simple Array.prototype.reduce() function:

const data = {
  "one": {
    "two": {
       "three": 3
     }
  }
};

const keys = ["one", "two", "three"];

const value = keys.reduce((a, v) => a[v], data);

console.log(value);

answered Apr 15 '19 at 09:22

Robby Cornelissen

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Cid · Answer 2 · 2019-04-15T09:34:17.907

You can use MyObject["fieldName"] to access the sub object. And then, you can use a recursive function that will use the array containing the indexes to roam through the object

let MyObj = {
  "one": {
    "two": {
       "three": 3
     }
  }
};

let Keys = ["one", "two", "three"];

function getValue(obj, arrIndexes, index = 0)
{
  let currentIndex = arrIndexes[index];
  let currentObject = obj[currentIndex];
  
  if (index < arrIndexes.length - 1)
  {
    return getValue(currentObject, arrIndexes, index + 1)
  }
  else
  {
    return currentObject;
  }
}

console.log(getValue(MyObj, Keys));

How to access property of nested object given dynamic keys?

2 Answers2