Original subtitles

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It's now finally time 2

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for your very first coding challenge. 3

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So coding challenges are basically coding exercises 4

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that you have to code on your own, 5

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and they are super important for you to test 6

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and reinforce all the skills 7

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that you just learned before. 8

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That's why there are dozens of coding challenges 9

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in this course, because students love them and they are one 10

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of the best ways of learning. 11

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And so this is the coding challenge number one 12

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of the section or coding exercise 13

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if you prefer to call it that. 14

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Now all of these coding challenges are also 15

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in a separate PDF file 16

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that is available somewhere 17

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in the course. 18

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So you can also get this text from there. 19

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You don't have to read the video. 20

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Okay. Now, anyway, the exercise is this 21

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Mark and John are trying 22

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to compare their body mass indexes and the BMI 23

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is calculated using this formula. 24

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So BMI is equal to mass divided by the height squared. 25

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Okay. 26

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And so squared is the exponentiation operator that we talked 27

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about before with the two. 28

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Okay. 29

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And so that is also the same 30

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to mass equals height times height. 31

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Okay. 32

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So this part is the same as this one. 33

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So you can choose 34

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to calculate the BMI either way. 35

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Now, what matters is that a mass needs to be 36

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in kilograms and to height needs to be in meters. 37

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So it's not gonna work 38

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with the U.S measures like feet and pound, 39

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but that's why I have the test data here already 40

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with the correct measurements. 41

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Anyway, here is what I want you to do for this challenge. 42

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One, you should store mark's and John's mass 43

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and height in variables, 44

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and you should do this for test data one. 45

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So this data here 46

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and then also for test data two, all right, 47

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then using these variables calculate both 48

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their BMI's using the formula that I just showed you. 49

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And again, you can use either one, 50

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it's gonna work the same way. 51

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Of course, to then check these values if they make sense, 52

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you can log them to the console, 53

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just like we have been doing up until this point. 54

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Then finally, I want you 55

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to create a Boolean variable called 'markHigherBMI', 56

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which will contain the information, 57

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whether Mark has a higher BMI than John. 58

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Okay. 59

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And this is actually similar to something 60

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that we did before So I hope that 61

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you can make this one work just fine. 62

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So now please really try to solve this problem on your own. 63

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And remember the advice that I gave you 64

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in the beginning. 65

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Don't try to make this perfect for now. 66

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What matters is really just to make it work. 67

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It doesn't matter if you write clean code 68

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or perfect code or efficient code, 69

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just make it work for now. 70

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All right. 71

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So pause the video now And I see you 72

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in a second with the solution. 73

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All right. 74

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I hope you manage to complete all the three Points 75

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of this challenge. 76

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And so here is 77

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how I would have implemented it. 78

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So I'm starting with number one, of course. 79

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And so let's say const massMark equals 78. 80

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Okay. 81

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So that's just, 82

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what is written here. 83

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And then heightMark equals one 69 84

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and then the same for John. 85

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So massJohn equals 92 86

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and then heightJohn equals one 95 now, right? 87

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And if you used different variable names, 88

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that's not a problem at all. 89

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As long as they are nicely descriptive, 90

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like these ones here, 91

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you're going to be fine. 92

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Also, you might've used a let here instead of const, 93

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because you might assume that these are values that 94

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are susceptible to change, 95

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especially here the mass, all right. 96

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However, I still decided to use const because I already know 97

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that I'm not going to change these values here 98

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throughout the program. 99

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And so just as we learned before, 100

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I prefer to always use const by default 101

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and I advise you 102

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to actually do the same. 103

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Okay. 104

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Anyway, let's now calculate the actual BMIs. 105

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So const BMIMark 106

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equals massMark divided, 107

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and let's check out the formula again, 108

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divided by the height squared. 109

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So that's going to be heightMark squared 110

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and then the BMIJohn So that's massJohn, 111

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and this time let's actually use the other formula. 112

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So this one here. 113

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So we're gonna use, heightJohn times heightJohn again. 114

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Okay. 115

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And now let's log both of them 116

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to the console here. 117

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So BMIMark and BMIJohn. 118

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And now we have an error here. 119

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Oh, of course I missed the dot log. 120

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Okay. 121

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Try it again. 122

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And here we go. 123

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So we see that BMIMark is higher 124

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than John's BMI. 125

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Okay. 126

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So I hope you got the same numbers here 127

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than I did. 128

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And if not, 129

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I guess you should probably check 130

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your code unless I have some mistake here. 131

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Let me check that actually. 132

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But I think everything is good. 133

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Okay. 134

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So if something is wrong, 135

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then please just let me know. 136

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All right. 137

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Now, if you implemented this 138

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in a different way, for example, 139

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you might not have created 140

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these separate variables here, 141

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then that's not a problem at all. 142

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Okay. 143

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You could have logged these calculations straight 144

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to the console. 145

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No problem at all. 146

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Again, what matters here is that you make this work and 147

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that in the end you get 148

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these same results here. 149

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Anyway, let's now also do step three 150

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and create a variable called 'markHigherBMI'. 151

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So let's just grab this here and const. 152

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And so what we're trying to figure out 153

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is if the BMI of Mark is higher than the BMI of John, right? 154

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And so that's what comparison operators are for, 155

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because remember that this one here will return either true 156

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or false. 157

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In our example, 158

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if BMI Mark is larger than one of John, 159

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then the result of this 160

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whole operator here will be true 161

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and otherwise it's gonna be false. 162

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Okay. 163

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So that's exactly what we did before 164

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in this example with the ages 165

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if I remember correctly. 166

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So where's that? It's right here. 167

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In this case, it was 'isFullAge' variable. 168

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Right? 169

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Okay. 170

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Anyway, let's log to your tutor console as well. 171

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And so we expect this one 172

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to be true, right? 173

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Because Mark's BMI is 27 and John's is 24. 174

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And so Mark's is larger and so the result 175

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of this should be true. 176

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So let's check that and indeed, 177

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we get true. 178

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Nice. 179

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So we basically solved it. 180

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Now I just want to do the same here for test data too. 181

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So we'll just copy this. 182

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So copy, and then I will simply comment 183

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out these first ones. 184

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So now I'm replacing these with 95, 185

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one 88 and then here for John, 186

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we have 85 and one 76. 187

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And the rest of course 188

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is the same. 189

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And that's the beauty of using variables 190

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because now all we have to do is to change 191

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these values in one place 192

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and then the changes will be propagated to the rest 193

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of the code here, 194

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which references these variables. 195

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Cool. 196

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So let's reload. 197

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And now BMI of John is 27. 198

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So it's a larger than 26.8. 199

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It's actually very close, but still, 200

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BMIMark is now lower 201

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than BMIJohn. 202

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So here we asked the question basically 203

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is BMIMark a larger 204

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than BMIJohn? 205

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And in this case it's not. 206

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So it's false. 207

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And so that's exactly the result 208

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that we get here. 209

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All right? 210

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So this one is solved and I hope you solved it as well. 211

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Again, it does not matter at all, 212

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if you did it in a different way, 213

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as long as the results were the same. 214

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So basically as long as you actually made it work. 215

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So, hopefully that was a lot of fun 216

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and you could practice your skillset little bit, 217

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which is really something essential 218

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to learn programming properly, 219

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without repetition and reinforcing your knowledge 220

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It's impossible, really to learn how to code. 221

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Anyway, see you now in the next video 222

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where we're going to continue learning the fundamentals 223

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of the beautiful JavaScript language.