0
1
00:00:00,270 --> 00:00:01,980
Hi guys. Welcome back.
1

2
00:00:02,040 --> 00:00:04,360
It's Angela from The App Brewery once more.
2

3
00:00:04,380 --> 00:00:10,470
So, in the last lesson we looked at the power of variables and how we can easily create them using the
3

4
00:00:10,490 --> 00:00:11,780
var keyword.
4

5
00:00:11,790 --> 00:00:17,730
Now in this lesson I want to cover some really important points about how you should name your variables
5

6
00:00:17,970 --> 00:00:21,210
so that you're in keeping with programming best practice.
6

7
00:00:21,210 --> 00:00:26,340
So currently I've still got the Snippets and the Console from the last lesson.
7

8
00:00:26,340 --> 00:00:31,140
Now this is a good point to show you that if you want to clear the console because it's getting a bit
8

9
00:00:31,140 --> 00:00:38,160
too messy or you're seeing too many messages, then you can simply hold down command and press K on Mac
9

10
00:00:38,400 --> 00:00:43,440
and on Windows you can hold down control and press K and this will clear your console.
10

11
00:00:43,530 --> 00:00:48,590
But remember this does not clear the information that's been stored inside the browser.
11

12
00:00:48,600 --> 00:00:55,840
So, for example, if I write myName again, it will still know that myName has the value of Angela.
12

13
00:00:55,920 --> 00:01:01,710
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

14
00:01:01,710 --> 00:01:04,290
all of our cache and delete all of the data.
14

15
00:01:04,440 --> 00:01:12,180
So to do that, on the Mac you can click and hold on the reload page and you will get this menu.
15

16
00:01:12,330 --> 00:01:16,800
So you have Normal Reload, Hard Reload, and Empty Cache and Hard Reload.
16

17
00:01:16,800 --> 00:01:21,670
So this is kind of like the supersized version of reloading.
17

18
00:01:21,810 --> 00:01:27,500
And on a PC you just simply need to right click on the reload button to get that menu.
18

19
00:01:27,690 --> 00:01:33,410
And now, if I click that, if I typed myName then it would not know what it is.
19

20
00:01:33,420 --> 00:01:36,150
It says it's undefined. It doesn't have a clue what it is.
20

21
00:01:36,150 --> 00:01:40,380
So we've managed to successfully clear all of the memory of any data.
21

22
00:01:40,380 --> 00:01:46,730
So let's go ahead and delete what's inside our Snippets as well so that we start off with an empty slate.
22

23
00:01:46,980 --> 00:01:53,750
And what I want to show you is that there are some rules that govern how you should name your variables.
23

24
00:01:53,760 --> 00:02:01,320
Now so far we've been naming our variables myName, or yourName, and that kind of makes sense for the context
24

25
00:02:01,320 --> 00:02:02,690
that we've been using it in.
25

26
00:02:02,730 --> 00:02:06,510
But actually it doesn't matter what you call your name.
26

27
00:02:06,630 --> 00:02:09,480
You could call it any string you like,
27

28
00:02:09,480 --> 00:02:11,960
and Javascript really doesn't care.
28

29
00:02:12,120 --> 00:02:20,160
But if I ask you what do you think yolsdjsj means, what would you say? If accidentally I've managed
29

30
00:02:20,160 --> 00:02:25,670
to actually write a real word in Icelandic, because it's distinctly possible,
30

31
00:02:25,800 --> 00:02:30,110
then maybe it'll have a meaning for the Icelandic students out there.
31

32
00:02:30,210 --> 00:02:33,610
But for most people this doesn't make any sense.
32

33
00:02:33,690 --> 00:02:41,860
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

34
00:02:41,940 --> 00:02:44,740
but you can see that this is a really really bad idea.
34

35
00:02:44,820 --> 00:02:51,630
So just because Javascript doesn't care doesn't mean that we don't care. We should care a lot, because
35

36
00:02:51,630 --> 00:02:56,810
imagine working on the same project as as some guy who likes to call his variables
36

37
00:02:56,820 --> 00:02:57,480
kasdkj
37

38
00:02:57,490 --> 00:02:58,590
ahsdjk,
38

39
00:02:58,800 --> 00:03:04,880
and you have to figure out what all of these things mean. You know, what exactly is Angela?
39

40
00:03:04,950 --> 00:03:07,470
Is it, what does it mean,
40

41
00:03:07,470 --> 00:03:08,050
right?
41

42
00:03:08,220 --> 00:03:14,550
It's kind of like if you only speak English and wǒ zhǐ huì shuō zhōngwén, it would be pretty hard for us
42

43
00:03:14,550 --> 00:03:16,660
to be friends or work together,
43

44
00:03:16,680 --> 00:03:17,490
right?
44

45
00:03:17,490 --> 00:03:25,470
So always give meaningful names to your variables and remember that with great power comes great responsibility,
45

46
00:03:25,650 --> 00:03:26,700
or even better,
46

47
00:03:26,700 --> 00:03:32,570
remember that the next person who has to look after your code could very well be an axe murderer.
47

48
00:03:32,640 --> 00:03:36,720
So there are some common rules that good programmers will follow,
48

49
00:03:37,020 --> 00:03:43,890
first of which is, give your variables meaningful names so that anybody can figure out quite easily what
49

50
00:03:43,890 --> 00:03:47,020
is the data that's likely to be stored inside it.
50

51
00:03:47,160 --> 00:03:52,890
It's like if you had named all of your folders on your desktop untitled folder 1, 2, 3, 4,
51

52
00:03:52,890 --> 00:03:58,560
5, 6, then you will be spending hours and hours digging through each of these folders trying to find
52

53
00:03:58,560 --> 00:04:00,270
the things that you're looking for.
53

54
00:04:00,270 --> 00:04:06,720
And instead if you named it pictures or movies or documents then it would be a lot easier to try and
54

55
00:04:06,720 --> 00:04:08,580
figure out what they contain.
55

56
00:04:08,580 --> 00:04:11,110
And it's the same story here with variable naming.
56

57
00:04:11,130 --> 00:04:16,440
So aside from this, there are certain things that Javascript will not let you do when you're trying to
57

58
00:04:16,440 --> 00:04:17,580
name your variables.
58

59
00:04:17,580 --> 00:04:24,960
So for example I can't call my variable var because this would be insanely confusing and Javascript
59

60
00:04:24,960 --> 00:04:27,390
does not actually allow you to do this.
60

61
00:04:27,420 --> 00:04:32,880
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

62
00:04:32,880 --> 00:04:39,290
this. But you can, however, have a variable name that contains keywords.
62

63
00:04:39,540 --> 00:04:46,680
So, for example, if you called it myvar, that's totally valid, and you can see from the coloring or the
63

64
00:04:46,680 --> 00:04:53,240
syntax highlighting, it's already showing you that this is valid, and this color is reserved for keywords.
64

65
00:04:53,250 --> 00:04:59,070
Now the other rule is that your variable name cannot begin with a number.
65

66
00:04:59,340 --> 00:05:02,160
So, for example, you can't call your variable
66

67
00:05:02,160 --> 00:05:03,290
123.
67

68
00:05:03,300 --> 00:05:05,770
This is also not allowed.
68

69
00:05:05,780 --> 00:05:13,920
However, like keywords, your variable name can contain numbers, so you can call it my123 and that's totally
69

70
00:05:13,920 --> 00:05:14,490
cool.
70

71
00:05:14,490 --> 00:05:23,140
The next rule is that your variable names can't contain spaces, so it can't be my name = "Angela".
71

72
00:05:23,490 --> 00:05:29,880
This makes absolutely no sense because it treats that space as if you're trying to write another different
72

73
00:05:29,880 --> 00:05:30,780
bit of code.
73

74
00:05:30,810 --> 00:05:38,400
The first word that comes after var and a space is going to be seen as the name of your variable.
74

75
00:05:38,410 --> 00:05:41,190
So your variable is called my,
75

76
00:05:41,190 --> 00:05:46,470
and so it doesn't know what to do with this extra name thing that you've squeezed in here.
76

77
00:05:46,620 --> 00:05:48,750
So no spaces basically.
77

78
00:05:48,840 --> 00:05:55,990
And finally the names can only contain letters, numbers, the dollar sign, and an underscore.
78

79
00:05:56,070 --> 00:06:00,580
No other symbols are valid for naming a variable.
79

80
00:06:00,780 --> 00:06:05,480
So, for example, you can't call your variable my-name.
80

81
00:06:05,490 --> 00:06:06,720
This is not valid.
81

82
00:06:06,780 --> 00:06:12,750
However, if you wish, you can call it my_name. That is a valid variable name.
82

83
00:06:12,750 --> 00:06:18,960
Now finally the last thing that you'll see me do throughout the course is that I will name all of my
83

84
00:06:18,960 --> 00:06:26,640
variables using camel casing and this means that I will start out the name with a lowercase word and
84

85
00:06:26,640 --> 00:06:30,050
then every subsequent word will be capitalized.
85

86
00:06:30,090 --> 00:06:36,980
And this is called camel casing, just as the camel humps are higher than its head, first word is not capitalized,
86

87
00:06:37,080 --> 00:06:43,450
and every subsequent one is. And the reason why this is really useful is because you avoid situations like
87

88
00:06:43,470 --> 00:06:49,980
TherapistFinder.com, which most people will read as TheRapistFinder.com.
88

89
00:06:49,980 --> 00:06:55,380
So make sure that when you're creating your own variables that you're following the same good practice
89

90
00:06:55,380 --> 00:07:01,350
that we've listed in this lesson. And in the next lesson there's a quick quiz just to test whether if
90

91
00:07:01,350 --> 00:07:08,670
you've remembered and embraced some of these rules regarding variable naming. So I'll see you on the
91

92
00:07:08,670 --> 00:07:09,460
next lesson.