Quiz: Reviewing JavaScript Object Orientation

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Reviewing JavaScript Object Orientation

?:

class Tree {
  constructor(type) {
    this.type = type;
  }
}

How would we create an instance of the above class?

( ) Tree.initialize(‘Oak’) (X) new Tree(‘Oak’) ( ) new Tree().constructor(‘Oak’) ( ) let oak = new Tree(); Tree.type = ‘Oak’

?: If we created an instance of Tree and stored it as the variable oak, how would we access the type property?

[ ] oak(‘type’) [ ] oak.properties(‘type’) [X] oak[‘type’] [X] oak.type

?: Once that instance is created, how would we modify the type property?

[X] oak.type = ‘maple’ [ ] oak.properties(‘type’) = ‘maple’ [ ] oak(‘type’) = ‘maple’ [X] oak[‘type’] = ‘maple’

?:

class Example {
  constructor(text) {
    this._text = text
  }
}

Above, we have an Example class. If we wanted to add a method called info() within the Example class, how would we write it?

( ) function info() { } (X) info() { } ( ) get info() { } ( ) set info() { }

?: Once we have defined our info() method, we might need to use the method somewhere else in our Example class. Choose the exact code necessary to access the info() method from within the Example class.

(X) this.info() ( ) self.info() ( ) example.info() ( ) Example.info()

?: The constructor within Example class assigns a variable _text to whatever is passed in when a new Example is created. If we wanted to create a getter method called text() to access this property, how would we write it?

( ) text() { return this._text } ( ) text = () => { return this._text } (X) get text() { return this._text } ( ) text = () => this._text

?: What code would we need to write in order to access our newly created getter method from within the Example class?

( ) example.text (X) this.text ( ) self.text ( ) Example.text

?: With a getter method, we can access the _text property indirectly. If we wanted to create a corresponding setter method, how would we write it?

( ) text(text) { this._text = text } ( ) text = (text) => { this._text = text } (X) set text(text) { this._text = text } ( ) text = (text) => this._text = text

?: Say we wanted to set our _text variable to ‘hello world!’ using our new setter class. From inside the Example class, what code would we need to write?

( ) this.text() = ‘hello world!’ ( ) this.text(‘hello world!’) (X) this.text = ‘hello world!’ ( ) example.text = ‘hello world!’

?:

let example = new Example()

If the example variable is assigned to a new instance of Example, how would we access the info() method using example? Write the exact code needed.

( ) this.info ( ) example.info ( ) this.info() (X) example.info()

?: We’ve also created a getter method, text. How would we access this method using the example variable?

( ) example.get(‘text’) (X) example.text ( ) example.get(“text”) ( ) This is not accessible

?: Using the setter method we created earlier, if we wanted to set _text to 'hello world!' using our example variable, how would we do it?

( ) example.text(‘hello world!’) (X) example.text = ‘hello world!’ ( ) example.text() = ‘hello world!’ ( ) this.text = ‘hello world!’

?: All class methods and properties are accessible from outside of the class.

(X) True ( ) False

?:

class House {
  constructor(address, owner) {
    this.address = address;
    this.owner = owner;
  }
}

let house1 = new House('81 Prospect St', 'Alan Turing');
let house2 = new House('11 Broadway', 'Grace Hopper');
house1.owner = 'Ada Lovelace';
house2.address = '1440 G St NW';

Imagine the code above executing. At the end, what is the value of the address property of house1?

(X) ‘81 Prospect St’ ( ) ‘11 Broadway’ ( ) ‘1440 G St NW’ ( ) ‘Ada Lovelace’

?: What is the address value of house2?

( ) ‘22 Elm St’ ( ) ‘11 Broadway’ (X) ‘1440 G St NW’ ( ) ‘Ada Lovelace’

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