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Let's talk about loops. So I have a while loop here, and with just a few lines of code, I can write this message all the way down the screen.

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If I go ahead and change the message like this, you know, to make it better

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all of them change.

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So how is this working? Well, we can revisit this code in a moment

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But first let's take a step back and think about how we might write this program

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using only what we know so far without using loops.

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So, to do that, we're really just gonna write a bunch of text over and over and over again right?

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We're gonna say text, message, I'll put it in the first place, and now it's just a matter of repeating this

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enough times so that eventually we get all the way to the bottom.

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And that's gonna take a lot of work, right?

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Because the bottom is really far away. And it's even worse if you

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then point out to me, hey, this wasn't actually 70, it needs to be closer, it needs to be at like

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60. And now that affects this one because it also needs to be smaller

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and all the way on, the more calls of text we have.

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And in fact, this way it's gonna take even longer to get to the bottom.

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So, this is really a pain, and thankfully we have loops to help us

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From now on, any time you see repetitive code like this, your first thought should be

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"Could I use a loop?" A loop will let us repeat this piece of code over and over and

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over again, making just little changes each time. So here's

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how we would rewrite this code with a loop. To get started, we need to type "while",

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the parentheses, and the curly braces. We're gonna get this message, but

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it's just because we're not done yet. Don't worry, it'll go away when we finish.

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So every time you write a loop you need to answer three key questions.

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And here they are: so,

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the first question is, "What do I want to repeat?" And

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whatever we want to repeat needs to go in-between these curlies.

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So we want to repeat the "text" call in this case, so go ahead and put that in here.

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But it's a little bit silly, right? Because right now we're just gonna be repeating

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the same call of text over and over, which is not really any good right, we need something to be

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changing. That brings us to question two, which is "What do I want to change each time?"

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So we want to change this "y" position, right? We want it to become 60 and then we want it

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to become 80. So we'll make that into a variable instead.

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Called y, because it's the y position. So we'll go ahead and declare a variable

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up here. I'll start it at 40. And now, finally, we just need to

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be changing y. We can do that down here, we can say "y gets y +

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"20" and it will be getting bigger every time. And in fact, we can use

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our lesson from incrementing shortcuts here. We can just go ahead

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and use the shortcut. So, this is fantastic, and we only

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need to do question three now, which is "How long should we be repeating this?"

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Well we want to do this over and over and over again, but we don't really want to do it forever, right?

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If we do it forever, first, that's a really long time to wait, and second, it might even crash your browser.

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But hopefully not. So really, we only

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want to do this until we get to the bottom of the page, right? Which means we wanna do it

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as long as y is less than 400. So we just put that in here, and there

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we have it! We have this message being written all the way down the screen.

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And you can see that this is way simpler than our previous approach, which, you know,

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took us about as long to write, but we weren't even a quarter of the way finished.

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So we can get rid of that, and there we have our program.

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Now, let's try to get a better understanding of what's going on. To do that, I'm going

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to print out y each time. I'm gonna say "y is now" and then down here

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I'll just tack y onto the end of the message so we can see it.

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So at the moment, the value is changing by 20, and we can change

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that just by changing this variable here. Or you can make it, you know, like,

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50. And now, now they're changing by 50. Similarly,

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you can go ahead and play with these other values and have them change. And

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you can see how that affects, you know, where the program stops.

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So, to understand this, you can think of it sort of

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like an "if" statement actually. We have our boolean expression in here

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just like you learned. And then, we do the body of the, um, the statement

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this part, only if the boolean is true, and otherwise we just jump to

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the end. But what's interesting is that with a while loop we actually

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have this secret thing going on at the bottom which says "go back to the start"

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"of the loop". And what this secret instruction means

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is that instead of leaving and just keeping on going, like with an "if"

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statement, every time we do the loop body we're going to go back and check

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if the condition is still true. And if it is, we're just going to repeat one

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more time. And just like you might have guessed, the second time we repeat, we're gonna do the same thing...

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we're gonna check hey, you know, go back to the start. Is y still less than

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279? And if it is, we'll repeat one more time and keep checking.

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And if it's not, we go back to the start here. And finally,

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we'll get to escape and keep going with our program.

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So great, there are a lot more interesting ways of using loops we're going to learn about soon, but

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for now, you are off to an excellent start.