Exercise Solutions: TypeScript

Part 1 - Declare Variables With Type

  1. Declare the variables with type based on the information given in the table.

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    let spacecraftName: string = 'Determination';
let speedMph: number = 17500;
let kilomitersToMars: number = 225000000;
let kilometersToTheMoon: number = 384400;
let milesPerKilometer: number = 0.621;

Part 2 - Print Days to Mars

  1. Use a template literal to print variables.

    console.log(`${spacecraftName} would take ${daysToMars} days to get to Mars.`);

Part 3 - Create a Function

  1. In the space indicated, define a function that calculates the days it would take to travel to a location.

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    function getDaysToLocation(kilometersAway: number): number {
   let milesAway: number = kilometersAway * milesPerKilometer;
   let hours: number = milesAway / speedMph;
   return hours / 24;
}

Part 4 - Create a Spacecraft Class

Create a Spacecraft class.

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class Spacecraft {
   milesPerKilometer: number = 0.621;
   name: string;
   speedMph: number;

   constructor(name: string, speedMph: number) {
      this.name = name;
      this.speedMph = speedMph;
   }

   getDaysToLocation(kilometersAway: number): number {
      let milesAway: number = kilometersAway * this.milesPerKilometer;
      let hoursToMars: number = milesAway / this.speedMph;
      return hoursToMars / 24;
   }
}

Part 5 - Export and Import the SpaceLocation Class

After following the steps in Part 5, your Spacecraft class should look slightly different:

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class Spacecraft {
   milesPerKilometer: number = 0.621;
   name: string;
   speedMph: number;

   constructor(name: string, speedMph: number) {
      this.name = name;
      this.speedMph = speedMph;
   }

   getDaysToLocation(kilometersAway: number): number {
      let milesAway: number = kilometersAway * this.milesPerKilometer;
      let hours: number = milesAway / this.speedMph;
      return hours / 24;
   }

   printDaysToLocation(location: SpaceLocation) {
      console.log(`${this.name} would take ${this.getDaysToLocation(location.kilometersAway)} days to get to ${location.name}.`);
   }
}