---
id: 56bbb991ad1ed5201cd392d0
title: Build JavaScript Objects
challengeType: 1
videoUrl: 'https://scrimba.com/c/cWGkbtd'
---
## 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 "name" is a string, "legs" and "tails" are numbers, and "friends" is an array.
## Tests
```yml
tests:
- text: myDog should contain the property name and it should be a string.
testString: assert((function(z){if(z.hasOwnProperty("name") && z.name !== undefined && typeof z.name === "string"){return true;}else{return false;}})(myDog), 'myDog should contain the property name and it should be a string.');
- text: myDog should contain the property legs and it should be a number.
testString: assert((function(z){if(z.hasOwnProperty("legs") && z.legs !== undefined && typeof z.legs === "number"){return true;}else{return false;}})(myDog), 'myDog should contain the property legs and it should be a number.');
- text: myDog should contain the property tails and it should be a number.
testString: assert((function(z){if(z.hasOwnProperty("tails") && z.tails !== undefined && typeof z.tails === "number"){return true;}else{return false;}})(myDog), 'myDog should contain the property tails and it should be a number.');
- text: myDog should contain the property friends and it should be an array.
testString: assert((function(z){if(z.hasOwnProperty("friends") && z.friends !== undefined && Array.isArray(z.friends)){return true;}else{return false;}})(myDog), 'myDog should contain the property friends and it should be an array.');
- text: myDog should only contain all the given properties.
testString: assert((function(z){return Object.keys(z).length === 4;})(myDog), 'myDog should only contain all the given properties.');
```
## Challenge Seed
```js
// Example
var ourDog = {
"name": "Camper",
"legs": 4,
"tails": 1,
"friends": ["everything!"]
};
// Only change code below this line.
var myDog = {
};
```
### After Test
```js
(function(z){return z;})(myDog);
```
## Solution
```js
var myDog = {
"name": "Camper",
"legs": 4,
"tails": 1,
"friends": ["everything!"]
};
```