Extra Practice

Remember: Learning to program takes practice! It helps to see concepts over and over, and it's always good to try things more than once. We learn much more the second time we do something. Use the exercises and additional self-checks below to practice.

1. Creating Classes and Class Instances

Review the code, then answer the questions below.

class Road {
    constructor(directions=['east','west'],sidewalk=true){
        this.directions = directions;
        this.numLanes = directions.length;
        this.sidewalk = sidewalk;
    }
}

let cityRoad = new Road(['north','north','south','south'], true);

let countryRoad = new Road(['east','west'], false);

2. Extending Classes

Review the code, then answer the questions below.

class Vehicle {
    constructor(license='ES64EVA'){
        this.license = license;
    }
    move(direction){
        console.log(`Vehicle ${this.license} moves ${direction}`);
    }
    get description(){
        return `Vehicle ${this.license} is a shapeless carriage.`;
    }

}

class Car extends Vehicle {
    constructor(license, numAxles=2, numWheels=4){
        super(license);
        this.numAxles = numAxles;
        this.numWheels = numWheels;
    }
    move(direction){
        return `Vehicle ${this.license} rolls ${direction}`;
    }
    get description(){
        return `Vehicle ${this.license} is a car with ${this.numAxles} axles and ${this.numWheels} wheels.`;
    }
}
class Airplane extends Vehicle {
    constructor(license, numWings=2, numPropellers=1){
        super(license);
        this.numWings = numWings;
        this.numPropellers = numPropellers;
    }
    move(direction){
        return `Vehicle ${this.license} flies ${direction}`;
    }
    get description(){
        return `Vehicle ${this.license} is an airplane with ${this.numWings} wings and ${this.numPropellers} propellers.`;
    }
}

let myCar = new Car('HOTWLZ1');

let myPlane = new Airplane('FLYIN1', 4);