added constants, comments

exercise_1.js

@@ -1,23 +1,30 @@
+'use strict'
+
 let shuttleName = 'Determination';
-let shuttleSpeed = 17500;
-let kilometersToMars = 225000000;
-let kilometersToMoon = 384400;
-let milesPerKilometer = 0.621;
+let shuttleSpeedMph = 17_500;
+const DISTANCE_TO_MARS_KM = 225_000_000;
+const DISTANCE_TO_MOON_KM = 384_400;
+const MILES_PER_KM = 0.621;
+const HOURS_PER_DAY = 24;
 
 console.log(typeof shuttleName);
-console.log(typeof shuttleSpeed);
-console.log(typeof kilometersToMars);
-console.log(typeof kilometersToMoon);
-console.log(typeof milesPerKilometer);
+console.log(typeof shuttleSpeedMph);
+console.log(typeof DISTANCE_TO_MARS_KM);
+console.log(typeof DISTANCE_TO_MOON_KM);
+console.log(typeof MILES_PER_KM);
 
-let milesToMars = (kilometersToMars * milesPerKilometer);
-let hoursToMars = (milesToMars / shuttleSpeed);
-let daysToMars = (hoursToMars / 24);
+let milesToMars = DISTANCE_TO_MARS_KM * MILES_PER_KM;
+let hoursToMars = milesToMars / shuttleSpeedMph;
+let daysToMars = hoursToMars / HOURS_PER_DAY;
 
-let milesToMoon = (kilometersToMoon * milesPerKilometer);
-let hoursToMoon = (milesToMoon / shuttleSpeed);
-let daysToMoon = (hoursToMoon / 24);
+let milesToMoon = DISTANCE_TO_MOON_KM * MILES_PER_KM;
+let hoursToMoon = milesToMoon / shuttleSpeedMph;
+let daysToMoon = hoursToMoon / HOURS_PER_DAY;
 
 
 console.log(shuttleName + ' will take ' + daysToMars.toFixed(2) + ' days to reach Mars ');
+/* 
+console.log('${shuttleName} will take ${daysToMars} days to reach Mars'); kan ook.
+.toFixed() verandert de primitive value van daysToMars naar een object.
+*/
 console.log(shuttleName + ' will take ' + daysToMoon.toFixed(2) + ' days to reach the Moon ');