1
00:00:00,700 --> 00:00:05,322
So far, the conditional statements we've
created provide just two possible paths.

2
00:00:05,322 --> 00:00:08,300
Let's call them door number one,
door number two.

3
00:00:08,300 --> 00:00:12,260
If a condition is true, like the user
entered a name in an input field,

4
00:00:12,260 --> 00:00:14,590
the program passes
through door number one.

5
00:00:14,590 --> 00:00:18,390
But if the condition is false, then the
program passes through door number two.

6
00:00:19,840 --> 00:00:22,480
But what if you want many
different outcomes, not just two?

7
00:00:23,990 --> 00:00:27,270
In our daily lives,
we're used to many possible outcomes.

8
00:00:27,270 --> 00:00:29,720
For example,
say it's your day off from work and

9
00:00:29,720 --> 00:00:32,145
you're trying to figure out what to do for
the day.

10
00:00:32,145 --> 00:00:34,610
Your first step might be to find
out what the weathers like?

11
00:00:34,610 --> 00:00:36,150
Based on this, you could plan your day.

12
00:00:37,270 --> 00:00:38,590
For example, if it's hot and

13
00:00:38,590 --> 00:00:42,900
sunny, you might go swimming, if it's
snowing, you might go sliding or skiing.

14
00:00:42,900 --> 00:00:45,350
If it's raining,
you might stay in and read a book.

15
00:00:45,350 --> 00:00:50,890
You can't do all three, only one, and each
choice is based on a series of conditions.

16
00:00:50,890 --> 00:00:54,180
If it's hot and sunny,
if it's snowing, if it's raining.

17
00:00:55,580 --> 00:00:57,490
JavaScript also includes a way for

18
00:00:57,490 --> 00:01:02,020
a program to provide multiple outcomes
using what's called an else if clause.

19
00:01:03,440 --> 00:01:08,554
All right, now let's open the else-if.js
file inside the js folder and

20
00:01:08,554 --> 00:01:14,268
as usual, update the script tag and
index.html so that it points to else-if.js

21
00:01:17,716 --> 00:01:21,550
So else if works like this,
you start with an if statement.

22
00:01:22,850 --> 00:01:27,820
Then add an else if clause,
which provides another condition to test.

23
00:01:27,820 --> 00:01:30,080
So now you have two conditions.

24
00:01:30,080 --> 00:01:32,020
If the first one is true,

25
00:01:32,020 --> 00:01:36,430
then the code in the first block
between the first pair of braces runs.

26
00:01:36,430 --> 00:01:38,480
Let's call this door number one.

27
00:01:38,480 --> 00:01:43,950
However, if the first condition is false,
then we test a second condition.

28
00:01:43,950 --> 00:01:46,230
If the answer to that condition is true,

29
00:01:46,230 --> 00:01:49,330
then the code in the second
code block runs.

30
00:01:49,330 --> 00:01:50,690
Let's call this door number two.

31
00:01:51,760 --> 00:01:56,340
The second condition is not tested
if the first condition is true.

32
00:01:56,340 --> 00:01:57,570
This is important.

33
00:01:57,570 --> 00:02:02,500
You'll only get to the second
condition if the first is false.

34
00:02:02,500 --> 00:02:07,570
Now, if neither of the conditions is true,
you might want to provide a fallback,

35
00:02:07,570 --> 00:02:10,600
door number three, so
that the program does something.

36
00:02:10,600 --> 00:02:13,098
You can do this by adding
an else clause to the end.

37
00:02:15,828 --> 00:02:19,970
Notice how there is no condition for
this last part.

38
00:02:19,970 --> 00:02:24,342
However, the code block at
the end only ever runs if both of

39
00:02:24,342 --> 00:02:26,853
the conditions above are false.

40
00:02:33,028 --> 00:02:37,140
And there's no limit to the number
of else if clauses you can add.

41
00:02:37,140 --> 00:02:40,860
But remember that you must
start with an if statement and

42
00:02:40,860 --> 00:02:44,760
the else clause, if there is one,
must go at the end.

43
00:02:44,760 --> 00:02:49,890
So now there is three test conditions and
four possible outcomes.

44
00:02:49,890 --> 00:02:54,730
And keep in mind that as soon as one
test condition is true, the code for

45
00:02:54,730 --> 00:02:58,170
that condition runs, and
all the conditions following,

46
00:02:58,170 --> 00:03:00,280
including the very last
else clause are skipped.

47
00:03:01,530 --> 00:03:05,150
Now, let's see how you might use this
conditional statement in a program.

48
00:03:05,150 --> 00:03:08,080
Earlier, I gave some examples of
activities you can do based on weather

49
00:03:08,080 --> 00:03:08,770
conditions.

50
00:03:08,770 --> 00:03:11,860
For instance, if it's snowing,
you could go sledding.

51
00:03:11,860 --> 00:03:15,354
Your first step might be to find
out what the weather is like,

52
00:03:15,354 --> 00:03:17,554
based on that you could plan your day.

53
00:03:17,554 --> 00:03:25,360
And the first condition, I'll check if
weather strictly equals the string, sun.

54
00:03:25,360 --> 00:03:31,119
If it's sun, log the message it's sunny,
so I'm going swimming.

55
00:03:39,874 --> 00:03:47,293
In the else if clause, I can check
if weather strictly equals rain.

56
00:03:49,674 --> 00:03:55,199
And if it's rain, log it's raining,
so I will read a book.

57
00:04:03,867 --> 00:04:10,775
I'll have the next else if clause
check if weather strictly equals snow.

58
00:04:13,395 --> 00:04:19,239
And if so, then log the message,
it's snowing, so I'm going sledding.

59
00:04:27,172 --> 00:04:31,816
Now, the else block at the end only
ever runs if all three of these

60
00:04:31,816 --> 00:04:34,190
conditions are false.

61
00:04:34,190 --> 00:04:38,203
In that case, log the message,
I don't know what I'm doing today.

62
00:04:47,366 --> 00:04:52,231
Before testing this code, I need to
declare the weather variable, and

63
00:04:52,231 --> 00:04:55,460
assign it either sun, rain, or snow.

64
00:04:55,460 --> 00:04:56,696
I'll try rain first.

65
00:04:59,153 --> 00:05:00,724
I'll save my code.

66
00:05:00,724 --> 00:05:04,951
And over in the console,
since weather = rain, I see the message,

67
00:05:04,951 --> 00:05:07,338
it's raining, so I will read a book.

68
00:05:10,109 --> 00:05:12,359
I'll try sun.

69
00:05:14,587 --> 00:05:15,622
Then snow.

70
00:05:19,900 --> 00:05:21,660
And it works.

71
00:05:21,660 --> 00:05:25,590
Now if I change the value of
weather to an empty string or

72
00:05:25,590 --> 00:05:29,700
anything other than rain,
sun, or snow, for example.

73
00:05:29,700 --> 00:05:32,720
The console prints,
I don't know what I'm doing today.

74
00:05:34,610 --> 00:05:38,945
So as you've learned, an else if clause
provides a way to make a program more

75
00:05:38,945 --> 00:05:42,830
flexible and able to respond on
to multiple conditional outcomes.