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Up to this point we learned the 'if' statement, the 'if else' statement and the 'else if' statement 

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And if you remember our section outline, well we haven't mentioned these two for javascript conditionals. 

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So we're going to tackle those today.

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As you can see we have two more to get through but don't be scared.

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These are not going to introduce anything new.

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There are just different ways of doing control flow but they won't do anything that a simple if else

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statement can't do.

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However there are cases where it will be much easier to do these two then if we do something with the

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'if else' statement.

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So let's check them out.

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The first thing we're going to talk about is the 'ternary operator'.

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It looks something like this,

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'condition ?'

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expression one (expr1) or expression two (expr2).

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And that is the syntax. It says, Is this true or false?

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If it's true then provide this value (expr1).

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If it's false provide this value(expr2).

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Let me show you an example of this, will have a function called 'isUserValid' that accepts a boolean (bool)

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and will just return the boolean value.

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Now within here we can say variable answer equals 'isUserValid' 

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and we'll say 'true' for now question mark(?)

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So if that's true I'll say 'You may enter'

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otherwise I'll say 'Access denied'

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Let me make this a little bit smaller so you can see.

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So again all we're saying is if this is true then do this expression("You may enter")

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If this is false do this expression("Access Denied").

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So just copy this into the console and see what happens.

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If I run 'anwer', Whoops I spell that wrong, 'answer'.

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I get, 'You may enter' because

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user is valid (isUserValid) is true.

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Now if I changed this to say 'false', well in that case I'll get 'Access denied'

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Let's do a little bit more of a complicated answer.

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We can say variable (var) 'automatedAnswer' and we can say and I'll do this on a new line just so you can see

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'Your account number is', 'isUserValid' and we'll just say something like.

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'false' for now.

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So because we have these brackets we're gonna have an expression inside of here that we can evaluate

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so we can say is user (isUserValid) is valid.

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If the user is valid will say '1234'.

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If not, we'll say 'not available'.

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If we copy and paste this here, into our console and we can see it better.

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We see, if user is valid (true)

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We want to say '1234'.

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If it's not then 'not available'.

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So if I run this and now I look at automated answer, I get 'Your account number is not available' well,

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because this user value is 'false'.

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But if I do 'true' well in that case your account number is '1234'.

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Now you might notice that this is actually not that different from if you did,

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'function condition' was called a condition and will say

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'if isUserValid' return.

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'You may enter'

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and you did 'else'

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'return Access denied' this function over here, 'condition', if I say variable(var) 'answer2' equals 'condition'.

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Let's see what happens.

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Copy these two, run them, and now if I look at the 'answer' I get 'You may enter' if I get the 'answer2'

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I get 'You may enter'.

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Now it's the exact same thing other than well bit of mis-spelling on my part.

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But you see that one way is a lot nicer, It's just nice simple one line. A ternary operator is really really

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good for these 'if else' where there is a check for a condition and there's two possible expressions, 

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that come out of it.

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All right let's learn, the next one, which is the 'switch' statement.

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This is the fun one.

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So a s'witch' statement looks something like this.

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And we can build a simple game right now to demonstrate how it works.

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I can say function 'moveCommand'.

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And we'll say it accepts parameter 'direction' within this function.

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I'll say variable(var) 'whatHappens' and we'll say 'switch'.

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Notice that it's a key word.

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So it's now highlighted in red.

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And I'll say 'direction'.

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The 'switch' statement is gonna accept 'direction' it's going to check 'direction'.

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And within here we'll say 'case' 'forward' which means check 'direction' if 'direction' equals 'forward',

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Then 'whatHappens' equals

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'You encounter a monster;'

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'break;'.

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I'll explain more 'break' does right after I finish up the rest of the case statements.

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So case statements as you can see are really good because I can just copy and paste.

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And now I can say for here we'll say 'back' and if direction is 'back' we'll say 'You arrived home' if the

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direction is 'right' in that case we'll say 'You found a river' and if the 'direction' is 'left' we'll say 

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'You run into a troll'.

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And then finally we'll say 'default'

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'whatHappens' equals to 'please enter a valid direction'.

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And we'll end it with a 'return' 'whatHappens'.

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All right.

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That was a whole lot of code.

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Let's run this command first and then we'll explain exactly what is happening.

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Copy the code.

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Copy into the console.

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And now we have the 'moveCommand'

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And if you remember the last video 'moveCommand' now exists in the root scope which is window, 

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so within here.

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Let's just say 'forward', now if I run this I get, 'You encountered a monster'.

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If I go 'back', 'You arrived home'.

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If I go 'right', 'You found a river'.

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If I go 'left', 'You run into a troll' and if I write jibberish

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I get.

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'Please enter a valid direction'.

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That's what switch statements are really good for when you have a lot of conditions.

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Instead of using an 'if else', 'if else', 'if else', 'if else', 'if else' statement, you can use a 'switch' statement

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and you can see, it reads nicely.

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Essentially what it's saying is create variable 'whatHappens' then switch.

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I want you to check whatever the condition is, whatever the variable is, in this case that's the direction.

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And in case, the direction equals 'forward' do this, in case direction is 'back' do this.

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If it's 'right' do this, if it's 'left' do this.

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And it says 'default' is if none of these conditions work and remember the program goes line by line

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so it checks 'forward' then it checks 'back' and it checks 'right' and the checks 'left'.

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And if nothing of those match then it says you can just default to 'please enter a valid direction' and

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then we return 'whatHappenes' so that was so that the function returns something for us.

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Now finally what is the 'break' well the 'break'(s) simply says,

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If 'case' is 'forward' then assign 'you encounter a monster' to

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'whatHhappens' variable and then 'break', 'break' is just saying break out of the switch statement.

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So instead of the program then checking to see if 'case' is 'back', 'case' is 'right', 'case' is 'left' or 'default'.

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If we say 'break', the program stops here and then goes straight out of the switch statement

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to return 'whatHappens'.

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So if I actually do, 'break' before 'whatHappens', 'you encounter a monster' and I copy this

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and let's rerun the function, we'll say 'moveCommand' is 'forward' notice what happens now.

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I get 'undefined' because we broke the program enters saying, Oh yeah!

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He typed in 'forward' but before we're able to assign something to the variable I say 'break', 

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I exit out of the switch statement and I return 'whatHappens' which it's only been declared but it's unassigned.

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So I just return 'undefined'.

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All right there you have it, your two other conditionals and you've covered all of them in javascript.

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Now each one is good for its own individual case but they're all very useful.

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I'll see you in the next one 
Buh-bye.