1 00:00:01,310 --> 00:00:03,560 Now it's time to practice everything 2 00:00:03,560 --> 00:00:06,990 that you just learned about ES6 classes, 3 00:00:06,990 --> 00:00:10,113 and so let's now do coding challenge number two, 4 00:00:11,470 --> 00:00:12,990 and the goal of this one 5 00:00:12,990 --> 00:00:16,560 is to basically recreate challenge number one, 6 00:00:16,560 --> 00:00:20,210 but this time using an ES6 class, 7 00:00:20,210 --> 00:00:21,610 then besides that, 8 00:00:21,610 --> 00:00:24,320 I also want you to add a getter, 9 00:00:24,320 --> 00:00:26,990 which should be called speedUS, 10 00:00:26,990 --> 00:00:29,700 and this one should return the current speed 11 00:00:29,700 --> 00:00:31,850 in miles per hour. 12 00:00:31,850 --> 00:00:34,100 So remember that the original speed 13 00:00:34,100 --> 00:00:36,500 is in kilometers per hour, 14 00:00:36,500 --> 00:00:39,700 and people in the US are usually not used to that, 15 00:00:39,700 --> 00:00:43,253 and so we can create a special getter called speedUS, 16 00:00:44,120 --> 00:00:47,060 and to do the conversion from kilometers per hour 17 00:00:47,060 --> 00:00:51,083 to miles per hour, all you need to do is to divide by 1.6, 18 00:00:52,590 --> 00:00:54,900 then you should also implement a setter 19 00:00:54,900 --> 00:00:57,600 with the same name of speedUS 20 00:00:57,600 --> 00:01:00,510 so that people can basically set the speed 21 00:01:00,510 --> 00:01:02,440 also in miles per hour, 22 00:01:02,440 --> 00:01:05,770 but of course, that value should then be stored in the class 23 00:01:05,770 --> 00:01:07,830 as kilometers per hour, 24 00:01:07,830 --> 00:01:09,950 and so before storing the value, 25 00:01:09,950 --> 00:01:12,183 you need to multiply it by 1.6, 26 00:01:13,620 --> 00:01:17,450 so to convert it back to kilometers per hour, 27 00:01:17,450 --> 00:01:20,590 and then take this test data, number one here, 28 00:01:20,590 --> 00:01:23,400 and create a new car and experiment 29 00:01:23,400 --> 00:01:27,260 with all of the methods and getters and setters. 30 00:01:27,260 --> 00:01:29,270 So have some fun with this one, 31 00:01:29,270 --> 00:01:31,923 and I'll see you back here once you are ready. 32 00:01:36,180 --> 00:01:37,440 Okay. 33 00:01:37,440 --> 00:01:41,160 So hopefully you did that without any problems 34 00:01:41,160 --> 00:01:43,940 and you don't even need my solution, 35 00:01:43,940 --> 00:01:45,673 but of course, as always, 36 00:01:46,760 --> 00:01:48,840 I will still show it to you, 37 00:01:48,840 --> 00:01:52,580 and what I'm gonna do is to simply copy the code 38 00:01:52,580 --> 00:01:54,440 that we wrote earlier, 39 00:01:54,440 --> 00:01:57,190 and I will then convert it to a class 40 00:01:57,190 --> 00:01:59,373 because that's actually not that hard. 41 00:02:00,230 --> 00:02:03,620 So here, we just need to call it a class 42 00:02:05,240 --> 00:02:08,603 and let me call it cl again for class, 43 00:02:10,211 --> 00:02:11,170 and okay. 44 00:02:11,170 --> 00:02:13,260 So then the curly braces, 45 00:02:13,260 --> 00:02:16,353 so one in the beginning, one in the end, 46 00:02:17,240 --> 00:02:20,633 then this function is actually called the constructor, 47 00:02:21,640 --> 00:02:24,000 and the rest is the same. 48 00:02:24,000 --> 00:02:26,510 Here we don't need these, don't need these, 49 00:02:26,510 --> 00:02:30,750 and here we don't need the prototype, 50 00:02:30,750 --> 00:02:33,900 so that's the whole point of using classes, 51 00:02:33,900 --> 00:02:36,543 and then we don't need this function, 52 00:02:37,420 --> 00:02:40,790 and besides that, that's actually it. 53 00:02:40,790 --> 00:02:42,900 So that's the constructor function 54 00:02:42,900 --> 00:02:46,780 plus the methods that we added to its prototype property 55 00:02:46,780 --> 00:02:49,380 simply converted to a class. 56 00:02:49,380 --> 00:02:52,380 And all right, so that was pretty easy. 57 00:02:52,380 --> 00:02:56,223 Now let's talk about the speedUS getter and setter. 58 00:02:59,890 --> 00:03:03,370 So first up the getter, which is easier. 59 00:03:03,370 --> 00:03:08,370 So speedUS and this one does not need any input 60 00:03:10,030 --> 00:03:14,800 and it will simply return this.speed 61 00:03:16,230 --> 00:03:17,743 and then divide it by 1.6, 62 00:03:18,930 --> 00:03:22,073 as I instructed up there in the text. 63 00:03:23,440 --> 00:03:27,440 Alright, and let's already test this now, 64 00:03:27,440 --> 00:03:29,860 and the test data here is Ford 65 00:03:29,860 --> 00:03:33,023 going at 120 kilometers per hour. 66 00:03:35,940 --> 00:03:38,500 So that's a new CarCl 67 00:03:39,970 --> 00:03:41,830 with the make of Ford 68 00:03:41,830 --> 00:03:43,783 and a speed of 120. 69 00:03:44,920 --> 00:03:47,693 So let's accelerate here a little bit, 70 00:03:51,940 --> 00:03:53,130 but before we do that, 71 00:03:53,130 --> 00:03:57,810 let's actually also read the speed in the US, 72 00:03:57,810 --> 00:04:02,810 because I actually know that 120 is 75 miles per hour, 73 00:04:03,370 --> 00:04:05,933 and so then I can know if this actually worked, 74 00:04:07,300 --> 00:04:10,340 and this one here is simply returns the value, 75 00:04:10,340 --> 00:04:12,553 and so we need to log it to the console. 76 00:04:14,070 --> 00:04:15,300 And all right, 77 00:04:15,300 --> 00:04:20,300 so indeed this 75 here coming from line 270 78 00:04:20,790 --> 00:04:24,060 is this speedUS property, 79 00:04:24,060 --> 00:04:27,730 So again, we basically transformed a method here 80 00:04:27,730 --> 00:04:29,020 into a property 81 00:04:30,250 --> 00:04:33,960 so that we read like this by using a getter, 82 00:04:33,960 --> 00:04:38,730 then we accelerate a little bit, so we increase to 130, 83 00:04:38,730 --> 00:04:42,993 and so that means that these methods, they keep working, 84 00:04:44,680 --> 00:04:49,570 and so our conversion to a class a works flawlessly. 85 00:04:49,570 --> 00:04:50,730 And now to finish, 86 00:04:50,730 --> 00:04:54,060 let's just implement the setter here as well. 87 00:04:54,060 --> 00:04:55,650 So set speedUS, 88 00:04:56,712 --> 00:04:58,660 and then remember we always need 89 00:04:58,660 --> 00:05:00,723 to take exactly one argument, 90 00:05:02,840 --> 00:05:05,590 so that's gonna be the speed, of course, 91 00:05:05,590 --> 00:05:08,640 and so here, we want to set the speed, 92 00:05:08,640 --> 00:05:11,690 but of course, in kilometers per hour, 93 00:05:11,690 --> 00:05:15,133 and so we take the speed and multiply it by 1.6, 94 00:05:17,060 --> 00:05:21,060 and so now if we do ford.speed 95 00:05:22,560 --> 00:05:24,613 equals 50 miles per hour, 96 00:05:25,860 --> 00:05:29,033 then let's take a look at the ford object, 97 00:05:30,570 --> 00:05:33,253 and here of course, it needs to be US. 98 00:05:35,110 --> 00:05:39,460 All right, and so here we set the speed to 50, 99 00:05:39,460 --> 00:05:42,030 and then what we get here is 80, 100 00:05:42,030 --> 00:05:46,143 and so 80 is indeed 50 times 1.6. 101 00:05:48,600 --> 00:05:51,733 And so I think that's actually it. 102 00:05:53,080 --> 00:05:53,913 And yeah. 103 00:05:55,170 --> 00:05:57,303 So challenge number two completed.