freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-data-structures/modify-an-object-nested-within-an-object.md

id, title, challengeType, forumTopicId

id	title	challengeType	forumTopicId
587d7b7c367417b2b2512b19	Modify an Object Nested Within an Object	1	301164

Description

Now let's take a look at a slightly more complex object. Object properties can be nested to an arbitrary depth, and their values can be any type of data supported by JavaScript, including arrays and even other objects. Consider the following:

let nestedObject = {
  id: 28802695164,
  date: 'December 31, 2016',
  data: {
    totalUsers: 99,
    online: 80,
    onlineStatus: {
      active: 67,
      away: 13,
      busy: 8
    }
  }
};

nestedObject has three properties: id (value is a number), date (value is a string), and data (value is an object with its nested structure). While structures can quickly become complex, we can still use the same notations to access the information we need. To assign the value 10 to the busy property of the nested onlineStatus object, we use dot notation to reference the property:

nestedObject.data.onlineStatus.busy = 10;

Instructions

Here we've defined an object userActivity, which includes another object nested within it. Set the value of the online key to 45.

Tests

tests:
  - text: <code>userActivity</code> should have <code>id</code>, <code>date</code> and <code>data</code> properties.
    testString: assert('id' in userActivity && 'date' in userActivity && 'data' in userActivity);
  - text: <code>userActivity</code> should have a <code>data</code> key set to an object with keys <code>totalUsers</code> and <code>online</code>.
    testString: assert('totalUsers' in userActivity.data && 'online' in userActivity.data);
  - text: The <code>online</code> property nested in the <code>data</code> key of <code>userActivity</code> should be set to <code>45</code>
    testString: assert(userActivity.data.online === 45);
  - text: The <code>online</code> property should be set using dot or bracket notation.
    testString: 'assert.strictEqual(code.search(/online: 45/), -1);'

Challenge Seed

let userActivity = {
  id: 23894201352,
  date: 'January 1, 2017',
  data: {
    totalUsers: 51,
    online: 42
  }
};

// Only change code below this line

// Only change code above this line

console.log(userActivity);

Solution

let userActivity = {
  id: 23894201352,
  date: 'January 1, 2017',
  data: {
    totalUsers: 51,
    online: 42
  }
};

userActivity.data.online = 45;