Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 1 00:00:01,094 --> 00:00:02,350 line:15% And here it is, 2 2 00:00:02,350 --> 00:00:03,830 line:15% the final coding challenge 3 3 00:00:03,830 --> 00:00:06,023 line:15% about object oriented programming. 4 4 00:00:08,170 --> 00:00:09,550 And in this challenge, 5 5 00:00:09,550 --> 00:00:13,640 the goal is to recreate the challenge number 3, 6 6 00:00:13,640 --> 00:00:16,840 but this time using ES6 classes. 7 7 00:00:16,840 --> 00:00:18,830 So basically what you should do, 8 8 00:00:18,830 --> 00:00:22,270 is to create a class EV, 9 9 00:00:22,270 --> 00:00:23,920 so electric vehicle. 10 10 00:00:23,920 --> 00:00:25,798 Which is going to be a child class, 11 11 00:00:25,798 --> 00:00:30,670 of the car class that we already created before as well. 12 12 00:00:30,670 --> 00:00:33,180 Then in that EV class, 13 13 00:00:33,180 --> 00:00:36,170 make the charge property private. 14 14 00:00:36,170 --> 00:00:37,538 So that's number two. 15 15 00:00:37,538 --> 00:00:40,590 And then point number three, 16 16 00:00:40,590 --> 00:00:43,360 is that I want you to implement the ability 17 17 00:00:43,360 --> 00:00:47,490 to chain the accelerate and charged battery methods 18 18 00:00:47,490 --> 00:00:49,240 on this class. 19 19 00:00:49,240 --> 00:00:53,323 And the same also for the brake method in the car class. 20 20 00:00:54,230 --> 00:00:56,863 So that's actually called CarCL. 21 21 00:00:58,740 --> 00:01:02,220 So then go ahead and experiment with chaining, 22 22 00:01:02,220 --> 00:01:04,390 and all of that should be done 23 23 00:01:04,390 --> 00:01:07,230 using this test data down here. 24 24 00:01:07,230 --> 00:01:08,550 All right. 25 25 00:01:08,550 --> 00:01:11,480 So I already have to coat here. 26 26 00:01:11,480 --> 00:01:12,930 And so this makes it a bit easier 27 27 00:01:12,930 --> 00:01:15,880 to understand what the goal is. 28 28 00:01:15,880 --> 00:01:16,890 So, as I mentioned, 29 29 00:01:16,890 --> 00:01:20,600 we already have the CarCL class from before, 30 30 00:01:20,600 --> 00:01:23,150 and so this one is basically going to stay the same, 31 31 00:01:23,150 --> 00:01:25,290 except for the break method, 32 32 00:01:25,290 --> 00:01:27,173 which I want you to make chainable. 33 33 00:01:28,230 --> 00:01:31,380 And then here we have the EV already, 34 34 00:01:31,380 --> 00:01:36,090 as we implemented it previously using constructor functions. 35 35 00:01:36,090 --> 00:01:38,340 And so the big goal of this challenge, 36 36 00:01:38,340 --> 00:01:40,830 is basically to convert all of this, 37 37 00:01:40,830 --> 00:01:44,003 into a child class of the CarCL class. 38 38 00:01:48,090 --> 00:01:48,923 All right, 39 39 00:01:50,100 --> 00:01:51,903 so let's do this. 40 40 00:01:53,430 --> 00:01:57,460 So class EVCL, 41 41 00:01:57,460 --> 00:01:59,740 and now this should be a child class. 42 42 00:01:59,740 --> 00:02:03,220 And so we use the extends keyword. 43 43 00:02:03,220 --> 00:02:06,633 So this extends the CarCL class. 44 44 00:02:08,150 --> 00:02:11,780 And now let's put this curly brace actually down here, 45 45 00:02:11,780 --> 00:02:14,232 because all we need to do is to now modify this 46 46 00:02:14,232 --> 00:02:15,363 a little bit. 47 47 00:02:16,720 --> 00:02:20,440 So here we can transform this here 48 48 00:02:20,440 --> 00:02:22,343 into the constructor. 49 49 00:02:23,870 --> 00:02:25,374 So the constructor method, 50 50 00:02:25,374 --> 00:02:29,683 and we still need to make speed and charge Of course. 51 51 00:02:30,660 --> 00:02:34,000 Now here we don't need to call the car, 52 52 00:02:34,000 --> 00:02:36,220 but instead we call super. 53 53 00:02:36,220 --> 00:02:38,550 Remember, and we do that of course, 54 54 00:02:38,550 --> 00:02:40,510 without the disc keyword, 55 55 00:02:40,510 --> 00:02:41,720 because all of this 56 56 00:02:41,720 --> 00:02:44,083 will automatically happen behind the scenes. 57 57 00:02:46,240 --> 00:02:48,600 Okay. So if I save this now, 58 58 00:02:48,600 --> 00:02:50,250 we get to this error, 59 59 00:02:50,250 --> 00:02:51,360 but that's because 60 60 00:02:51,360 --> 00:02:54,423 we still have a lot of stuff to change down here. 61 61 00:02:55,700 --> 00:02:58,500 Next here is linking off the prototypes. 62 62 00:02:58,500 --> 00:03:02,200 And none of this is necessary with classes, 63 63 00:03:02,200 --> 00:03:05,540 because all of this simply happens automatically 64 64 00:03:05,540 --> 00:03:06,633 behind the scenes. 65 65 00:03:07,840 --> 00:03:10,400 We also don't need to set anything manually 66 66 00:03:10,400 --> 00:03:12,290 on the prototype properties. 67 67 00:03:12,290 --> 00:03:14,213 So let's get rid of this. 68 68 00:03:15,100 --> 00:03:16,090 And in here also, 69 69 00:03:16,090 --> 00:03:17,983 we don't need to function keyword. 70 70 00:03:20,037 --> 00:03:21,840 And so with this, 71 71 00:03:21,840 --> 00:03:24,863 uh, I think for now we should be good to go. 72 72 00:03:26,180 --> 00:03:29,940 So let's now create an object called Rivian, 73 73 00:03:29,940 --> 00:03:34,273 which is going at 120 with a charge of 23%. 74 74 00:03:35,960 --> 00:03:37,170 So Rivian, 75 75 00:03:37,170 --> 00:03:42,081 which is, uh, another electric vehicle brand. 76 76 00:03:42,081 --> 00:03:47,081 So EVCL Rivian 120 and 23% of charge. 77 77 00:03:51,350 --> 00:03:52,743 Let's check it out here, 78 78 00:03:54,100 --> 00:03:56,873 and yup, there it is. 79 79 00:03:58,890 --> 00:04:00,300 Great. 80 80 00:04:00,300 --> 00:04:02,380 So next up the task, 81 81 00:04:02,380 --> 00:04:04,653 is to make the charge private. 82 82 00:04:06,240 --> 00:04:07,463 So let's do that. 83 83 00:04:08,770 --> 00:04:10,390 So this is the CarCL. 84 84 00:04:10,390 --> 00:04:13,520 So here we don't have to charge in the parent class, 85 85 00:04:13,520 --> 00:04:16,550 but we do have it here in the child class. 86 86 00:04:16,550 --> 00:04:18,230 Now we receive this charge, 87 87 00:04:18,230 --> 00:04:20,680 actually as an input here. 88 88 00:04:20,680 --> 00:04:23,500 And so we still need to define 89 89 00:04:23,500 --> 00:04:27,000 all the fields outside of any method. 90 90 00:04:27,000 --> 00:04:28,600 So we do that up here, 91 91 00:04:28,600 --> 00:04:32,490 and that is true for both private and public fields. 92 92 00:04:32,490 --> 00:04:33,323 So in this case, 93 93 00:04:33,323 --> 00:04:34,563 we want a private field, 94 94 00:04:35,410 --> 00:04:37,360 and that's called charge, 95 95 00:04:37,360 --> 00:04:39,620 and then we don't give it any value. 96 96 00:04:39,620 --> 00:04:41,973 And here we simply reassign that. 97 97 00:04:43,160 --> 00:04:47,190 And then all we have to do is to change it everywhere. 98 98 00:04:47,190 --> 00:04:51,093 So that's here and here and here, 99 99 00:04:52,130 --> 00:04:53,083 give it a save. 100 100 00:04:55,210 --> 00:04:56,493 If we now check this, 101 101 00:04:58,460 --> 00:05:00,600 then indeed here it is. 102 102 00:05:00,600 --> 00:05:02,053 And we didn't get any error, 103 103 00:05:03,390 --> 00:05:07,880 but indeed, as we try to now access this property outside, 104 104 00:05:07,880 --> 00:05:10,610 then that is not going to work. 105 105 00:05:10,610 --> 00:05:12,730 So it is now truly private, 106 106 00:05:12,730 --> 00:05:16,560 and it is encapsulated inside of the class. 107 107 00:05:16,560 --> 00:05:17,740 So from outside, 108 108 00:05:17,740 --> 00:05:19,680 there is no way of changing it, 109 109 00:05:19,680 --> 00:05:24,680 except of course by charging the battery or by accelerating. 110 110 00:05:24,880 --> 00:05:26,560 And so once again, 111 111 00:05:26,560 --> 00:05:30,090 this method here is basically a public API, 112 112 00:05:30,090 --> 00:05:31,640 so that we can manipulate 113 113 00:05:31,640 --> 00:05:34,520 the charge property from the outside. 114 114 00:05:34,520 --> 00:05:37,970 But without being able to directly access the property 115 115 00:05:37,970 --> 00:05:39,253 from the outside. 116 116 00:05:41,590 --> 00:05:43,010 So next up, 117 117 00:05:43,010 --> 00:05:45,070 we want to implement a chaining 118 118 00:05:45,070 --> 00:05:48,373 on accelerate, chargeBattery and brake. 119 119 00:05:49,590 --> 00:05:50,423 So on brake, 120 120 00:05:50,423 --> 00:05:52,430 we need to do it here. 121 121 00:05:52,430 --> 00:05:53,520 And so remember, 122 122 00:05:53,520 --> 00:05:58,520 all we have to do is to return this keyword, right? 123 123 00:05:59,190 --> 00:06:00,463 So that's very easy, 124 124 00:06:01,620 --> 00:06:02,693 here to same, 125 125 00:06:03,800 --> 00:06:04,633 this. 126 126 00:06:05,830 --> 00:06:07,825 And again, we are doing this here, 127 127 00:06:07,825 --> 00:06:12,825 basically on all the methods that actually set something. 128 128 00:06:15,060 --> 00:06:17,373 And so that's why this makes the most sense. 129 129 00:06:19,370 --> 00:06:23,490 Great. So now we are able to do something like this. 130 130 00:06:23,490 --> 00:06:25,593 So we can accelerate, 131 131 00:06:27,120 --> 00:06:29,640 and then we can accelerate again, 132 132 00:06:29,640 --> 00:06:33,010 and we can accelerate again maybe. 133 133 00:06:33,010 --> 00:06:35,630 Let's brake for a change, 134 134 00:06:35,630 --> 00:06:37,343 then let's charge the battery, 135 135 00:06:38,620 --> 00:06:41,710 let's say to 50%, 136 136 00:06:41,710 --> 00:06:43,510 and then let's accelerate some more. 137 137 00:06:45,650 --> 00:06:49,363 And so this is what the result is going to be looking like. 138 138 00:06:50,840 --> 00:06:53,800 So here we are accelerating three times, 139 139 00:06:53,800 --> 00:06:57,900 then we are breaking down by five kilometers per hour, 140 140 00:06:57,900 --> 00:06:59,200 and then immediately, 141 141 00:06:59,200 --> 00:07:02,860 we add 20 kilometers per hour back again. 142 142 00:07:02,860 --> 00:07:05,200 And the charge then drops to 49. 143 143 00:07:05,200 --> 00:07:08,963 And that's because previously we had charged it to 50. 144 144 00:07:11,600 --> 00:07:14,610 And what's also interesting to see here, 145 145 00:07:14,610 --> 00:07:18,520 is that, or child class does also inherit 146 146 00:07:18,520 --> 00:07:22,190 the getters and setters from the parent class. 147 147 00:07:22,190 --> 00:07:25,223 So we can also do this. 148 148 00:07:26,740 --> 00:07:27,730 So remember, 149 149 00:07:27,730 --> 00:07:32,593 that is a setter and a getter that we defined previously. 150 150 00:07:34,240 --> 00:07:39,051 And so this is basically 195 kilometers per hour, 151 151 00:07:39,051 --> 00:07:41,960 converted to miles per hour. 152 152 00:07:41,960 --> 00:07:44,570 Okay. And with that, 153 153 00:07:44,570 --> 00:07:47,230 this challenge is now completed. 154 154 00:07:47,230 --> 00:07:49,520 And I think we used all the things 155 155 00:07:49,520 --> 00:07:53,360 that we learned over the course of this section 156 156 00:07:53,360 --> 00:07:56,200 right here in all of these four challenges. 157 157 00:07:56,200 --> 00:07:58,780 So this should cover everything that you learned. 158 158 00:07:58,780 --> 00:07:59,760 And so by now, 159 159 00:07:59,760 --> 00:08:01,910 you actually already put everything 160 160 00:08:01,910 --> 00:08:04,910 that we learned about object oriented programming 161 161 00:08:04,910 --> 00:08:07,380 into practice by yourself. 162 162 00:08:07,380 --> 00:08:09,530 So congratulations for that. 163 163 00:08:09,530 --> 00:08:11,440 That was a really great job, 164 164 00:08:11,440 --> 00:08:12,680 and a great effort 165 165 00:08:12,680 --> 00:08:15,173 to watch this entire section until the end. 166 166 00:08:16,020 --> 00:08:19,930 And now it's time to make this even more exciting 167 167 00:08:19,930 --> 00:08:21,160 and to do that, 168 168 00:08:21,160 --> 00:08:24,210 we will create an entire brand new project, 169 169 00:08:24,210 --> 00:08:26,800 which will be completely based on objects 170 170 00:08:26,800 --> 00:08:28,500 in the next section. 171 171 00:08:28,500 --> 00:08:30,060 So that project is going to be 172 172 00:08:30,060 --> 00:08:31,870 one of the most exciting things 173 173 00:08:31,870 --> 00:08:34,510 of this course, in my opinion. 174 174 00:08:34,510 --> 00:08:36,660 So I hope to see you there soon, 175 175 00:08:36,660 --> 00:08:38,230 once you're finished, 176 176 00:08:38,230 --> 00:08:41,250 basically digesting this section. 177 177 00:08:41,250 --> 00:08:43,520 So congratulations once again. 178 178 00:08:43,520 --> 00:08:46,070 I'm really happy to still have you with me, 179 179 00:08:46,070 --> 00:08:48,200 here at this point of the course. 180 180 00:08:48,200 --> 00:08:51,693 And so I see you back here in the next section. 14474