1 00:00:01,200 --> 00:00:04,430 And here goes your next coding challenge. 2 00:00:04,430 --> 00:00:06,180 This time number three, 3 00:00:06,180 --> 00:00:09,863 for you to review all the material about objects. 4 00:00:11,490 --> 00:00:13,320 And I hope that you're really doing 5 00:00:13,320 --> 00:00:15,340 all these coding challenges. 6 00:00:15,340 --> 00:00:17,310 Because as I mentioned earlier, 7 00:00:17,310 --> 00:00:20,900 they are really, really important for your progress. 8 00:00:20,900 --> 00:00:23,430 And I designed them all very carefully 9 00:00:23,430 --> 00:00:26,110 to exactly match the progress of the course 10 00:00:26,110 --> 00:00:30,200 and place them in strategic points of the curriculum. 11 00:00:30,200 --> 00:00:33,260 So I cannot stress enough how important it is 12 00:00:33,260 --> 00:00:37,130 that you do these challenges even if it's a bit difficult 13 00:00:37,130 --> 00:00:40,200 but that's why they are called challenges. 14 00:00:40,200 --> 00:00:43,580 They are really to challenge you and to make a thing 15 00:00:43,580 --> 00:00:47,060 and if necessary spent half an hour or one hour 16 00:00:47,060 --> 00:00:51,260 even to really try to figure out how the code works 17 00:00:51,260 --> 00:00:52,900 without coding on your own, 18 00:00:52,900 --> 00:00:55,823 it's impossible to learn programming, believe me. 19 00:00:56,690 --> 00:01:00,300 But anyway, let's now get to the challenge. 20 00:01:00,300 --> 00:01:04,620 And in this one, we're going back to Mark and John comparing 21 00:01:04,620 --> 00:01:07,020 their body mass indexes. 22 00:01:07,020 --> 00:01:09,400 And this time we're gonna use objects 23 00:01:09,400 --> 00:01:11,960 to implement these calculations. 24 00:01:11,960 --> 00:01:16,250 So here we have the formula again to calculate the BMI. 25 00:01:16,250 --> 00:01:21,030 And so your tasks are, first for each of them, 26 00:01:21,030 --> 00:01:25,250 so for Mark and John create an object with properties 27 00:01:25,250 --> 00:01:29,150 for their full name, their mass and their height. 28 00:01:29,150 --> 00:01:33,880 So their full names are actually Mark Miller and John Smith. 29 00:01:33,880 --> 00:01:38,880 Then create a method called calcBMI on each object 30 00:01:39,580 --> 00:01:43,150 which will then calculate the BMI based on the data 31 00:01:43,150 --> 00:01:45,080 that is on the object. 32 00:01:45,080 --> 00:01:48,890 So create the both method and add the exact same method 33 00:01:48,890 --> 00:01:50,600 to both objects. 34 00:01:50,600 --> 00:01:54,000 So write this method first in one of the objects 35 00:01:54,000 --> 00:01:56,160 and then copy the exact same method 36 00:01:56,160 --> 00:01:58,980 without changing it to the other object. 37 00:01:58,980 --> 00:02:01,820 And this method should store the BMI value 38 00:02:01,820 --> 00:02:06,160 to a property and it should also return it from the method. 39 00:02:06,160 --> 00:02:09,180 So a little bit like the cogH method 40 00:02:09,180 --> 00:02:11,070 that we did in the previous lecture 41 00:02:11,070 --> 00:02:14,970 then lock to the console who of the two has to hire a BMI 42 00:02:16,356 --> 00:02:19,760 and this string should look like this. 43 00:02:19,760 --> 00:02:22,760 So it should include the full name 44 00:02:22,760 --> 00:02:24,800 and actually here it's not the full name 45 00:02:24,800 --> 00:02:29,040 but do include the full name that's why we have it. 46 00:02:29,040 --> 00:02:34,040 So John Smith BMI is higher than Mark Miller's. 47 00:02:37,250 --> 00:02:41,300 So not killers, but Mark Millers 48 00:02:41,300 --> 00:02:45,450 and then also include the actual BMI value here. 49 00:02:45,450 --> 00:02:46,836 And here is the test data 50 00:02:46,836 --> 00:02:51,320 and I believe it's the same data as before. 51 00:02:51,320 --> 00:02:54,470 So good luck with this challenge. 52 00:02:54,470 --> 00:02:56,550 And again, it might be challenging 53 00:02:56,550 --> 00:03:00,320 but please give it a try anyway, okay. 54 00:03:00,320 --> 00:03:02,170 So I see you here in a minute 55 00:03:02,170 --> 00:03:05,110 or maybe in half an hour, who knows? 56 00:03:05,110 --> 00:03:06,933 It doesn't matter how long you take. 57 00:03:09,020 --> 00:03:12,610 Now, okay, so let's get to work. 58 00:03:12,610 --> 00:03:17,610 So number one is creating an object for each of them. 59 00:03:18,600 --> 00:03:20,593 So object Mark. 60 00:03:24,170 --> 00:03:28,763 So full name property, Mark Miller, 61 00:03:30,100 --> 00:03:34,730 then the mass which is 78 kilograms 62 00:03:35,820 --> 00:03:40,327 and then the height which is 1.69 meters. 63 00:03:42,360 --> 00:03:44,680 So that's it for now. 64 00:03:44,680 --> 00:03:47,743 And now I'm just gonna copy this, 65 00:03:48,930 --> 00:03:50,740 as always, I'm a bit lazy 66 00:03:50,740 --> 00:03:53,593 and that's just how programmers are, I guess. 67 00:03:54,860 --> 00:03:59,860 So John Smith and he is 92 kilos 68 00:04:02,700 --> 00:04:06,233 and 1.95 meters tall. 69 00:04:07,440 --> 00:04:10,980 Okay, so that is point number one. 70 00:04:10,980 --> 00:04:14,653 And now we will create the cog BMI method. 71 00:04:19,540 --> 00:04:22,870 And then a function without any parameters 72 00:04:22,870 --> 00:04:26,520 because we will take the data directly from the object 73 00:04:26,520 --> 00:04:30,670 just like we did it with the cog H method previously. 74 00:04:30,670 --> 00:04:33,800 And remember that it says here that we should store 75 00:04:33,800 --> 00:04:37,970 the BMI value to a property and also return it 76 00:04:37,970 --> 00:04:39,033 from the method. 77 00:04:40,330 --> 00:04:45,330 So this means that we will do this .BMI 78 00:04:45,590 --> 00:04:48,290 and then do the calculation here. 79 00:04:48,290 --> 00:04:51,730 And remember, from the formula to BMI is calculated 80 00:04:51,730 --> 00:04:56,730 by this .mass divided by this .height squared. 81 00:05:00,020 --> 00:05:03,430 So exponentiation operator with two 82 00:05:04,500 --> 00:05:06,980 and then also return it. 83 00:05:06,980 --> 00:05:08,480 So at this .BMI 84 00:05:11,050 --> 00:05:14,710 and just to see if this actually works, 85 00:05:14,710 --> 00:05:17,100 let's actually call this method. 86 00:05:17,100 --> 00:05:19,760 So mark.calc.BMI 87 00:05:21,110 --> 00:05:24,290 and now I will quickly lock to the console, 88 00:05:24,290 --> 00:05:26,680 the property that we just created. 89 00:05:26,680 --> 00:05:30,740 So I could have locked this to the console directly 90 00:05:30,740 --> 00:05:33,350 but I want to do it this way now. 91 00:05:33,350 --> 00:05:35,120 And it doesn't really matter. 92 00:05:35,120 --> 00:05:39,823 So with this, remember we created a property called BMI. 93 00:05:40,660 --> 00:05:43,340 And so that is now of course accessible here. 94 00:05:43,340 --> 00:05:48,340 So mark.BMI because remember that here in this method, 95 00:05:49,160 --> 00:05:53,970 this now points to Mark because that is the object 96 00:05:53,970 --> 00:05:55,800 that is calling the method 97 00:05:55,800 --> 00:06:00,270 and therefore this .BMI will be on Mark. 98 00:06:00,270 --> 00:06:05,270 So mark.BMI equals mark.mass divided by mark.height. 99 00:06:07,250 --> 00:06:11,053 And so that's how we get this data into this method. 100 00:06:13,350 --> 00:06:15,610 All right, so that's essentially what we learned 101 00:06:15,610 --> 00:06:17,090 in the last lecture. 102 00:06:17,090 --> 00:06:18,560 And so here I'm doing the same. 103 00:06:18,560 --> 00:06:20,670 I'm first calculating this value 104 00:06:20,670 --> 00:06:23,250 and then I'm doing mark.BMI 105 00:06:23,250 --> 00:06:26,740 which was added here in this method call. 106 00:06:26,740 --> 00:06:29,220 Of course without this method call, 107 00:06:29,220 --> 00:06:31,990 mark.BMI would not be available 108 00:06:31,990 --> 00:06:34,600 because this method here it doesn't call itself. 109 00:06:34,600 --> 00:06:36,343 We need to explicitly call it. 110 00:06:38,830 --> 00:06:42,113 Now, console are missing the .log. 111 00:06:43,230 --> 00:06:46,143 How can that still happen after all these years? 112 00:06:47,480 --> 00:06:52,480 Okay, so here we get the BMI of 27 which seems about right. 113 00:06:52,740 --> 00:06:55,700 And now as I said, we will simply go ahead 114 00:06:55,700 --> 00:07:00,700 and copy this method exactly the same to this John object 115 00:07:02,760 --> 00:07:06,480 and it will work just the same, believe me. 116 00:07:06,480 --> 00:07:08,143 So let me show that to you. 117 00:07:09,580 --> 00:07:14,103 So now we call John.calcBMI. 118 00:07:14,970 --> 00:07:19,360 And so now the object calling calcBMI is John. 119 00:07:19,360 --> 00:07:21,420 And so now in this method here, 120 00:07:21,420 --> 00:07:24,760 this will point to the John object. 121 00:07:24,760 --> 00:07:28,690 And so this time John.BMI will be calculated 122 00:07:28,690 --> 00:07:31,643 using John's data of mass and height. 123 00:07:32,810 --> 00:07:35,163 Okay, are you still following that? 124 00:07:36,040 --> 00:07:38,850 As always, you can pause the video, 125 00:07:38,850 --> 00:07:40,750 analyze the code on your own 126 00:07:40,750 --> 00:07:45,200 or you can always rewind to hear the explanation again. 127 00:07:45,200 --> 00:07:46,920 I actually like to do that myself 128 00:07:46,920 --> 00:07:49,723 when I watch other online video courses. 129 00:07:50,600 --> 00:07:53,363 So I think that's a good tip maybe. 130 00:07:54,800 --> 00:07:58,970 Anyway, so we just calculated the BMI of John here as well 131 00:07:58,970 --> 00:08:01,823 and so now I'm logging both to the console. 132 00:08:02,760 --> 00:08:06,130 And so yeah, this one also looks correct. 133 00:08:06,130 --> 00:08:09,780 And so this means that simply copying this method 134 00:08:09,780 --> 00:08:13,020 from one place to the other actually makes it work 135 00:08:13,020 --> 00:08:16,840 and adapt to the data of each objects. 136 00:08:16,840 --> 00:08:20,950 Now having the exact same code in both of these objects, 137 00:08:20,950 --> 00:08:25,820 kind of violates the don't repeat yourself principle, right. 138 00:08:25,820 --> 00:08:29,380 And actually there is a way in which we can avoid this. 139 00:08:29,380 --> 00:08:31,760 And of course we will learn how 140 00:08:31,760 --> 00:08:33,800 at a later point in the course 141 00:08:33,800 --> 00:08:37,320 using something called object oriented programming. 142 00:08:37,320 --> 00:08:39,590 But for now we are still learning the basics 143 00:08:39,590 --> 00:08:43,010 and just want to make things work. 144 00:08:43,010 --> 00:08:46,210 And of course have some fun along the way. 145 00:08:46,210 --> 00:08:49,190 So this was the hardest part I believe 146 00:08:49,190 --> 00:08:54,190 at least now all we have to do is to write this string here. 147 00:08:55,510 --> 00:08:56,840 Let me actually copy the examples 148 00:08:56,840 --> 00:08:59,633 so we have it as a reference down here. 149 00:09:00,600 --> 00:09:02,873 Otherwise I'm gonna get a bit lost. 150 00:09:05,370 --> 00:09:10,370 So if Mark.BMI is larger than John.BMI, then console.log. 151 00:09:21,640 --> 00:09:24,900 So let's get the full name now from the object. 152 00:09:24,900 --> 00:09:29,900 So mark.fullName BMI and now we also need it here 153 00:09:31,950 --> 00:09:33,690 in these parenthesis. 154 00:09:33,690 --> 00:09:37,570 So let's put it there, Mark.BMI is higher than 155 00:09:42,850 --> 00:09:45,093 and I'll let me just copy it here. 156 00:09:48,610 --> 00:09:51,610 So and again, I'm using command D 157 00:09:51,610 --> 00:09:53,830 to select the next occurrence 158 00:09:53,830 --> 00:09:57,310 and then let's just replace it with John. 159 00:09:57,310 --> 00:10:01,073 So Mark's BMI is higher than John's BMI. 160 00:10:02,920 --> 00:10:04,893 And now let's grab this again. 161 00:10:05,790 --> 00:10:10,790 Else if John BMI is larger than Mark.BMI 162 00:10:16,970 --> 00:10:19,483 then essentially say the opposite. 163 00:10:20,370 --> 00:10:25,370 So here it's gonna be John and again command D 164 00:10:27,220 --> 00:10:31,193 and here it's gonna be Mark, okay. 165 00:10:33,730 --> 00:10:38,730 So 27 is higher than 24 and that 27 belongs to Mark. 166 00:10:40,170 --> 00:10:44,270 And so this seems to be about right 167 00:10:44,270 --> 00:10:46,160 but it's not completely right. 168 00:10:46,160 --> 00:10:50,450 So of course here it should be lowercase. 169 00:10:50,450 --> 00:10:54,840 So BMI and now I cannot use the command D 170 00:10:54,840 --> 00:10:57,540 because then it will select this one as well. 171 00:10:57,540 --> 00:11:00,030 So I'm double clicking on this one 172 00:11:00,030 --> 00:11:01,250 and I hope that you're finding 173 00:11:01,250 --> 00:11:04,950 these VS code tips useful as well. 174 00:11:04,950 --> 00:11:09,040 So I'm clicking or actually I'm double clicking on this one, 175 00:11:09,040 --> 00:11:11,660 Then I hold down the command key 176 00:11:11,660 --> 00:11:14,080 which in your case might be the control key 177 00:11:14,080 --> 00:11:16,100 or maybe the option key. 178 00:11:16,100 --> 00:11:19,010 So I know there are different configurations for this 179 00:11:19,010 --> 00:11:20,900 and it might not even work for you. 180 00:11:20,900 --> 00:11:25,080 So please don't ask any question in that case 181 00:11:25,080 --> 00:11:27,530 but for me, I just have to hit command 182 00:11:27,530 --> 00:11:30,840 and then I can double click on multiple words 183 00:11:30,840 --> 00:11:32,990 and then all of them get selected. 184 00:11:32,990 --> 00:11:36,300 So now I have these four multiple cursors here again 185 00:11:36,300 --> 00:11:38,760 and I can simply delete all of them 186 00:11:38,760 --> 00:11:41,893 And right the one that I'm interested in. 187 00:11:43,200 --> 00:11:46,100 so that's the lowercase BMI 188 00:11:46,100 --> 00:11:48,630 and now we get to correct values 189 00:11:48,630 --> 00:11:53,630 And also this conditional logic is correct as well. 190 00:11:54,160 --> 00:11:58,090 And so it is we did actually solve the challenge 191 00:11:58,090 --> 00:12:00,910 and with this we also finished this introduction 192 00:12:00,910 --> 00:12:02,970 to JavaScript objects. 193 00:12:02,970 --> 00:12:06,200 And once again, I really want to congratulate you 194 00:12:06,200 --> 00:12:09,090 for the progress that you're making here. 195 00:12:09,090 --> 00:12:11,670 Great job and really well done. 196 00:12:11,670 --> 00:12:14,950 And I really mean it because I know how hard it is 197 00:12:14,950 --> 00:12:17,360 to stick to a course like this 198 00:12:17,360 --> 00:12:19,840 and to learn a completely new thing 199 00:12:19,840 --> 00:12:22,110 that is probably a bit confusing 200 00:12:22,110 --> 00:12:24,290 for you at this point still. 201 00:12:24,290 --> 00:12:28,790 Just keep in mind that that is absolutely no problem at all. 202 00:12:28,790 --> 00:12:31,940 And actually in the next section I believe, 203 00:12:31,940 --> 00:12:34,560 I have a video about how to learn, 204 00:12:34,560 --> 00:12:38,330 how to learn basically so about learning how to code. 205 00:12:38,330 --> 00:12:41,340 And there's a lot of great tips that I'm sharing there. 206 00:12:41,340 --> 00:12:45,360 So once you reach that, make sure to watch it carefully. 207 00:12:45,360 --> 00:12:48,020 But now anyway, I will leave you to review 208 00:12:48,020 --> 00:12:51,550 this lecture if you want or to move on together with me 209 00:12:51,550 --> 00:12:52,910 to the next video 210 00:12:52,910 --> 00:12:56,393 where we're now gonna start talking about loops.