Switch

Quick reference

• 00:04 So in the last video, we looked at If statements.
• 00:07 In this video, I wanna talk about switch.
• 00:09 And switch is similar to an If statement, but a little bit different.
• 00:12 So switch is a conditional, just like If and
• 00:14 else, but it allows you to select a bunch of different little blocks of code.
• 00:18 So, this is basically what a switch looks like.
• 00:21 We have, we call switch, and then we have an expression, and
• 00:24 then it's gonna test against each of these cases.
• 00:28 So, this may look a little bit weird, but it's actually pretty easy.
• 00:31 It starts out, like I said, it evaluates this expression.
• 00:35 And it compares each of these cases to that expression.
• 00:39 As soon as it matches to one, it executes whatever code is in here, and
• 00:43 then it ends.
• 00:44 This break is basically an end.
• 00:46 If it doesn't match, it goes down to the next one, and it tries to match it.
• 00:50 If it doesn't work, it goes through all the different cases.
• 00:52 And then finally,
• 00:53 if it doesn't match any of them, it spits some default code that you designate.
• 00:58 So let's just make one of these.
• 00:59 I'm gonna go, I'm gonna call var first name set that = to John.
• 01:05 So it's just creating a variable.
• 01:06 So now let's do a switch, and we just go switch, and then here's our expression.
• 01:11 I'm just gonna say firstName.
• 01:14 So it's just gonna pop in that variable right there.
• 01:17 So then we do that.
• 01:21 And now, we created our cases.
• 01:23 I'm just gonna do a couple of cases.
• 01:25 Let's go, John, and you put ;.
• 01:28 And then, the code that I wanna write,
• 01:32 the block of code, is just right here, so that's our first case.
• 01:37 Our next case will go, let's say, Mary, right?
• 01:41 And the same thing, so let's change this to Mary.
• 01:49 And then finally, let's do a default.
• 01:52 And, I don't know, let's go, document write, sorry I don't know you, first name.
• 01:58 So if we save this, and come up to our page, and hit reload,
• 02:02 we see nothing at all.
• 02:03 What have we done here?
• 02:05 I misspelled switch, S-W-I-T-C-H, all right.
• 02:11 And I'm just gonna pop these in, just to make it a little more readable.
• 02:15 So if we save this, now we come back, boom, Hello John!
• 02:18 If we change our variable from John to Mary, come up here, Hello Mary!
• 02:23 If we change it to Bob, we save this, sorry, I don't know you Bob.
• 02:30 So what it's doing here is,
• 02:31 it's taking our expression first name and it's testing each case.
• 02:35 It's saying, is our first name John?
• 02:37 If so, do this, else test to see if it's Mary.
• 02:42 Is our first name Mary?
• 02:43 If so, output this.
• 02:44 If not, no.
• 02:45 If you go through all of our different cases,
• 02:47 and we can have as many cases as we want.
• 02:49 And if none of them match, then we output this line of code right there.
• 02:53 So that's a basic switch.
• 02:54 Now notice, I put brakes under each one of these.
• 02:58 In an If - Else statement, we dont have to break out.
• 03:00 If a statement is true, the line gets executed and then the statements ends,
• 03:04 not so in a switch.
• 03:05 You have to explicitly tell a thing to break.
• 03:08 Except for you'll notice down here, I didn't, and
• 03:10 that's because this is the last one listed.
• 03:12 We could put our default anywhere we want.
• 03:13 We could list default right up here at the top.
• 03:16 And if we do, then we need to put a break there.
• 03:18 But since it's the last one, I can just leave it the way it is.
• 03:21 So, that's switch.
• 03:21 You can see it's sort of like an If - Else statement just formatted a bit
• 03:25 differently.
• 03:25 To tell you the truth, I rarely use switch.
• 03:28 I find that If - Else statements pretty much handle most of what I need them to do, but
• 03:32 every once in a while, there's a weird thing where this makes sense to use.
• 03:35 So anyway, that's switch.
• 03:37 In the next video, we'll start to look at for loops.

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