Original subtitles

0 Hi guys. Welcome back. 1

It's Angela from The App Brewery once more. 2

So, in the last lesson we looked at the power of variables and how we can easily create them using the 3

var keyword. 4

Now in this lesson I want to cover some really important points about how you should name your variables 5

so that you're in keeping with programming best practice. 6

So currently I've still got the Snippets and the Console from the last lesson. 7

Now this is a good point to show you that if you want to clear the console because it's getting a bit 8

too messy or you're seeing too many messages, then you can simply hold down command and press K on Mac 9

and on Windows you can hold down control and press K and this will clear your console. 10

But remember this does not clear the information that's been stored inside the browser. 11

So, for example, if I write myName again, it will still know that myName has the value of Angela. 12

So in order to clear all of the data we're going to have to do a hard clean. We're going to have to empty 13

all of our cache and delete all of the data. 14

So to do that, on the Mac you can click and hold on the reload page and you will get this menu. 15

So you have Normal Reload, Hard Reload, and Empty Cache and Hard Reload. 16

So this is kind of like the supersized version of reloading. 17

And on a PC you just simply need to right click on the reload button to get that menu. 18

And now, if I click that, if I typed myName then it would not know what it is. 19

It says it's undefined. It doesn't have a clue what it is. 20

So we've managed to successfully clear all of the memory of any data. 21

So let's go ahead and delete what's inside our Snippets as well so that we start off with an empty slate. 22

And what I want to show you is that there are some rules that govern how you should name your variables. 23

Now so far we've been naming our variables myName, or yourName, and that kind of makes sense for the context 24

that we've been using it in. 25

But actually it doesn't matter what you call your name. 26

You could call it any string you like, 27

and Javascript really doesn't care. 28

But if I ask you what do you think yolsdjsj means, what would you say? If accidentally I've managed 29

to actually write a real word in Icelandic, because it's distinctly possible, 30

then maybe it'll have a meaning for the Icelandic students out there. 31

But for most people this doesn't make any sense. 32

And when I try to use it or print it, I mean I can if I remember it exactly the way that I typed it, 33

but you can see that this is a really really bad idea. 34

So just because Javascript doesn't care doesn't mean that we don't care. We should care a lot, because 35

imagine working on the same project as as some guy who likes to call his variables 36

kasdkj 37

ahsdjk, 38

and you have to figure out what all of these things mean. You know, what exactly is Angela? 39

Is it, what does it mean, 40

right? 41

It's kind of like if you only speak English and wǒ zhǐ huì shuō zhōngwén, it would be pretty hard for us 42

to be friends or work together, 43

right? 44

So always give meaningful names to your variables and remember that with great power comes great responsibility, 45

or even better, 46

remember that the next person who has to look after your code could very well be an axe murderer. 47

So there are some common rules that good programmers will follow, 48

first of which is, give your variables meaningful names so that anybody can figure out quite easily what 49

is the data that's likely to be stored inside it. 50

It's like if you had named all of your folders on your desktop untitled folder 1, 2, 3, 4, 51

5, 6, then you will be spending hours and hours digging through each of these folders trying to find 52

the things that you're looking for. 53

And instead if you named it pictures or movies or documents then it would be a lot easier to try and 54

figure out what they contain. 55

And it's the same story here with variable naming. 56

So aside from this, there are certain things that Javascript will not let you do when you're trying to 57

name your variables. 58

So for example I can't call my variable var because this would be insanely confusing and Javascript 59

does not actually allow you to do this. 60

You can see that we've got this little error here and it already tells us that we can't structure our code like 61

this. But you can, however, have a variable name that contains keywords. 62

So, for example, if you called it myvar, that's totally valid, and you can see from the coloring or the 63

syntax highlighting, it's already showing you that this is valid, and this color is reserved for keywords. 64

Now the other rule is that your variable name cannot begin with a number. 65

So, for example, you can't call your variable 66

123. 67

This is also not allowed. 68

However, like keywords, your variable name can contain numbers, so you can call it my123 and that's totally 69

cool. 70

The next rule is that your variable names can't contain spaces, so it can't be my name = "Angela". 71

This makes absolutely no sense because it treats that space as if you're trying to write another different 72

bit of code. 73

The first word that comes after var and a space is going to be seen as the name of your variable. 74

So your variable is called my, 75

and so it doesn't know what to do with this extra name thing that you've squeezed in here. 76

So no spaces basically. 77

And finally the names can only contain letters, numbers, the dollar sign, and an underscore. 78

No other symbols are valid for naming a variable. 79

So, for example, you can't call your variable my-name. 80

This is not valid. 81

However, if you wish, you can call it my_name. That is a valid variable name. 82

Now finally the last thing that you'll see me do throughout the course is that I will name all of my 83

variables using camel casing and this means that I will start out the name with a lowercase word and 84

then every subsequent word will be capitalized. 85

And this is called camel casing, just as the camel humps are higher than its head, first word is not capitalized, 86

and every subsequent one is. And the reason why this is really useful is because you avoid situations like 87

TherapistFinder.com, which most people will read as TheRapistFinder.com. 88

So make sure that when you're creating your own variables that you're following the same good practice 89

that we've listed in this lesson. And in the next lesson there's a quick quiz just to test whether if 90

you've remembered and embraced some of these rules regarding variable naming. So I'll see you on the 91

next lesson.