Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll

Object-Oriented JavaScript: Challenge

Preview

Start a free Courses trial
to watch this video

Sign up for Treehouse

Game Class Constructor Method Solution

2:45 with Ashley Boucher

See the solution for the Game class constructor method.

Default Values

Default values are a way to initialize parameters with a specific value, even if no value or undefined is passed.

If an argument is passed for that parameter, the parameter will be initialized with the passed value.

If an argument is not passed, the parameter will be initialized with the default value.

In the following example, the company parameter has a default value of "Treehouse". If no third argument is sent when the function is called, the parameter company will still be available in the function, with a value of "Treehouse".

const name = 'Ashley';
const job = 'teacher';

printEmployee(name, job);

printEmployee(name, job, company = 'Treehouse') {
    //function code here
}

MDN Docs - Default Values

Related Discussions

Have questions about this video? Start a discussion with the community and Treehouse staff.

Sign up

    Related Discussions

    Have questions about this video? Start a discussion with the community and Treehouse staff.

    Sign up

    Welcome back. 0:00
    Now that the constructor method and createPlayers methods are written, 0:01
    you've finished the foundational parts of this game. 0:04
    Let's walk through the solution for these two methods, and 0:06
    then you'll be ready to move on to the next stage, rendering our game on screen. 0:09
    Navigate to your Game.js file. 0:14
    Once you're inside, double check that your Game class declaration matches what you 0:16
    see on screen. 0:20
    The constructor method for 0:21
    the Game class is rather straightforward, it receives no arguments. 0:23
    The first property is the board property. 0:27
    This is set to a new Board object. 0:29
    The players property will hold an array of two players. 0:32
    This property will be set to the return value from a call to the createPlayers 0:35
    method. 0:40
    We'll go over the solution for the createPlayers method in just a moment. 0:41
    The final property, the ready property, will be set to false. 0:45
    This means that when a game object is initialized, 0:49
    it automatically won't be ready to play or be interacted with. 0:52
    You'll see as we move forward with the game's development that the game state 0:55
    will change throughout a player's turn to prevent action on the game at 0:59
    certain times. 1:03
    Okay, you're done building constructor methods. 1:04
    Let's move on to the createPlayers method. 1:07
    You should have added this method inside your Game class declaration after 1:09
    the constructor method. 1:13
    The createPlayers method receives no arguments. 1:15
    It also doesn't require any loops like our other creator methods. 1:18
    All that's required is that the new player objects are created and 1:22
    returned in an array form the method. 1:26
    You can see that in the declaration of the players variable I instantiated both 1:28
    new Player objects inside an array. 1:33
    You could also see the arguments passed to the player constructor method for 1:35
    the name, id, color, and active parameters. 1:40
    If you're wondering about why there's no value for 1:43
    the active property in the initialization of the Player 2 object, 1:46
    it's because of something called default values. 1:49
    When declaring a function or method with parameters, 1:52
    you can set the parameter equal to something. 1:55
    So if no argument is sent, the parameter's value will default to whatever it was set 1:57
    to in the function declaration. 2:02
    In this case, the player constructor method has a parameter called active 2:03
    that's set to false. 2:08
    This means that if no argument is passed for the active parameter, 2:10
    that parameter will be set to false. 2:13
    I put a link to some documentation on default values inside of 2:15
    the teacher's notes if you'd like to learn more about them. 2:18
    Okay, great job. 2:22
    You've written the constructor methods for each of the five classes and 2:23
    initialized all of the objects except for one, the game. 2:27
    You might be wondering when this happens? 2:30
    How do we start our game? 2:32
    How do we connect it to something visual on the screen? 2:34
    How do our real-life users interact with our game? 2:36
    Join me in the following stages to get the answers to these questions. 2:40
    Keep on coding. 2:43

    You need to sign up for Treehouse in order to download course files.

    Sign up

      You need to sign up for Treehouse in order to set up Workspace

      Sign up