freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/build-javascript-objects.english.md

id, title, challengeType, videoUrl, forumTopicId

id	title	challengeType	videoUrl	forumTopicId
56bbb991ad1ed5201cd392d0	Build JavaScript Objects	1	https://scrimba.com/c/cWGkbtd	16769

Description

You may have heard the term object before. Objects are similar to arrays, except that instead of using indexes to access and modify their data, you access the data in objects through what are called properties. Objects are useful for storing data in a structured way, and can represent real world objects, like a cat. Here's a sample cat object:

var cat = {
  "name": "Whiskers",
  "legs": 4,
  "tails": 1,
  "enemies": ["Water", "Dogs"]
};

In this example, all the properties are stored as strings, such as - "name", "legs", and "tails". However, you can also use numbers as properties. You can even omit the quotes for single-word string properties, as follows:

var anotherObject = {
  make: "Ford",
  5: "five",
  "model": "focus"
};

However, if your object has any non-string properties, JavaScript will automatically typecast them as strings.

Instructions

Make an object that represents a dog called myDog which contains the properties "name" (a string), "legs", "tails" and "friends". You can set these object properties to whatever values you want, as long as "name" is a string, "legs" and "tails" are numbers, and "friends" is an array.

Tests

tests:
  - text: <code>myDog</code> should contain the property <code>name</code> and it should be a <code>string</code>.
    testString: assert((function(z){if(z.hasOwnProperty("name") && z.name !== undefined && typeof z.name === "string"){return true;}else{return false;}})(myDog));
  - text: <code>myDog</code> should contain the property <code>legs</code> and it should be a <code>number</code>.
    testString: assert((function(z){if(z.hasOwnProperty("legs") && z.legs !== undefined && typeof z.legs === "number"){return true;}else{return false;}})(myDog));
  - text: <code>myDog</code> should contain the property <code>tails</code> and it should be a <code>number</code>.
    testString: assert((function(z){if(z.hasOwnProperty("tails") && z.tails !== undefined && typeof z.tails === "number"){return true;}else{return false;}})(myDog));
  - text: <code>myDog</code> should contain the property <code>friends</code> and it should be an <code>array</code>.
    testString: assert((function(z){if(z.hasOwnProperty("friends") && z.friends !== undefined && Array.isArray(z.friends)){return true;}else{return false;}})(myDog));
  - text: <code>myDog</code> should only contain all the given properties.
    testString: assert((function(z){return Object.keys(z).length === 4;})(myDog));

Challenge Seed

var myDog = {
// Only change code below this line


// Only change code above this line
};

After Test

(function(z){return z;})(myDog);

Solution

var myDog = {
  "name": "Camper",
  "legs": 4,
  "tails": 1,
  "friends": ["everything!"]
};