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Hey, this is going to be a short bonus lesson on bubbling and capturing, we talked about it a little

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bit earlier.

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Well, we have our event handling that.

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We have an option to do true or false.

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And this lesson will give you a little bit more of an illustration of how it works.

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So by default, you don't have to include it anymore.

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You did have to before and by default will go to false.

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And it only really makes a difference when you have two events on the same element.

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So there might be a case where you've attached an event listener to the parent, but then the children

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also have events as well.

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And when you are adding these event listeners, you have the option to capture or bubble.

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So the difference between Katcher and bubble bubbling is the event is first captured and handled by

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the innermost element and then propagated to the outer elements in capturing is the opposite, where

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the event is first captured by the outermost element and propagated to the inner element.

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So what we're going to do in this lesson is show up, show you how you can set this up and how you can

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explore a little bit more about how it works.

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So creating an event later on, elements are going to create a bunch of divs.

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These debates are going to be inside each other.

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And as you can see, five is inside of four, which is inside a three, which is inside a two, which

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is inside of one.

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So all these elements are going to be contained within each other and they're also going to have event

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listeners.

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So that's going to have multiple event listeners on the same events.

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And I show you how it gets handled using the bubbling and capturing.

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So the code snippet is this one here where we've got all of the device and as we can see, the device

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one is inside or one is the main parent and then the next device inside, next one inside, inside,

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inside.

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And then we close off all the device and we've got section ID where we've got some output.

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So this is where we can track what's happening with the bubbling.

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We select all of the elements and we loop through.

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We add event listeners, so we add one capture, one bubble, and that's where we've got the function

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names.

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So they can be named anything, of course, because they're just functions and one is set to true and

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one is set to false.

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So that's the big difference here.

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That true and false, and this will clearly illustrate what the difference is.

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So let's try this out and open up our editors and create a fresh document.

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We're going to create all the different diffs.

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So we've got our first div and within here we're just going to have a value of one.

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Inside of that one, we're going to have another div and this one will have a value of two.

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And then inside of this div will have another div and this one will have a value of three.

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So I'm not sure really the best way to kind of output this in the HTML, but we have another div inside

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of here and I know it's kind of getting a little bit tight here on the screen.

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So we've got four and then we have another div and this one is five.

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So let me do a quick clean up of this so you can see it a little bit better.

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When we refresh it.

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All we see is one, two, three, four, five, because of course the device don't have any content

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in it as of yet.

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We're also going to create another area that we can create an output so we can call this one, give

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this one a section tag so that we don't get mistaken for the device.

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And this is going to be the only section tags we don't actually even have to give an ID.

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I'm going to just add the JavaScript in page.

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So right on this index page or just have the JavaScript on the page itself.

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So selecting the elements is the first thing that we want to do.

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So we've got our output elements and that should be const output elements.

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And then this is where we're going to select that element.

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We can use documents, query selector and we're going to select it by TAG and we have only one section

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so we can select that really easily.

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The other one, we need to select all of the elements.

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So just call it El's and documents using query selector all.

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So we're going to select all of the devs on the page so we can add all of the event listeners to that.

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Next, we're going to do a for loop and looping through.

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Letting X or Y equals zero and then looping through while ls length is less than I and will increment

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I by one, so we have a way out of our loop.

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And this is we're going to add all of the event listeners.

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But before we add event listeners, I want to actually add in some styles to these elements.

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A lot of times what I'll do is I'll set up a variable, so I'll call it L. And then within here I'll

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have Elles.

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So it looks a little bit cleaner when you do it this way.

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So now I can just reference the object as well.

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And we've got style and then border.

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So one pick solid red so that we can distinguish between all the different diffs.

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Also, El, it's always good practice to try adding in some styling.

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And of course I could have done this with scissors, but we do want to focus on JavaScript.

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So therefore a great way to practice JavaScript another style, add in some padding and this actually

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should be, I guess, not incrementing.

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So that's why it's only adding it to the one.

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So now we have something way more interesting and we see that we've got the same pattern that we were

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looking at within the example we can also set because this is an object so we can set values to it so

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we can have AI plus one.

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So that means that each one of these elements is now going to have kind of a hidden value there.

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We could also call it secret or something like that to make it more interesting.

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Adding an event listener event that we're listening for is a click.

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So this is going to be for the catcher.

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So make sure that you set this one to true and the other one is going to be for the bubble and calling

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in the function bubble and make sure you set this one to false.

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Otherwise, it won't work.

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So we've got our event listeners.

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And next, we need to create our functions.

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So we've got one function called bubble and then we have another function called capture.

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And within these functions, we're just going to update the output and I'll create a function in order

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to handle the output as well.

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So function we can call it output.

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It will take in value of message.

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And then with that message value, it's going to take the output element that we have on the pick and

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update the inner HTML with whatever content.

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So just add to that just a quick short format there and using a template, literal adding in the value

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of the variable message.

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And we can do a line break as well.

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And of course then the back.

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So ready to add in content into the message.

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So do a quick refresh, make sure there's no errors.

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So now we can output to the output function a message, some information, and in this case we're going

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to call it capture.

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And then the contents of what we're capturing is whatever is contained within this V so that's that

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value that we're set there.

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That's how we're just getting whatever value that's contained within there.

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We could also take the inter text as well if we wanted to.

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And actually this one should be bubble and this one is capture.

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So I just got them back.

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So I'll update that to be bubble and that one is capture.

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So let's try this and see what happens now.

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Whenever I click, you see that when I click on FI, what we're getting for capture.

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So we get all of the captures run.

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So starting at 1:00, so it starts at the outermost element and moves towards the innermost element,

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whereas the bubble starts at five over here and it goes through all the elements ending at one.

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So if we click one, we're only going to see one because one is it's also the outer and the inner.

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So that's why it doesn't really make any difference if you've only got the one event.

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But if we click number two, we're going to have two different events.

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So let me refresh that and I'll make the smaller I have it zoomed in quite a bit.

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So if I click two, you're going to see that on the capture.

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We're starting out one, two, and on the bubble we're doing two one.

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So that's the way that bubble and capture works.

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So let's take a little bit time to get used to it.

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And it is only really important now if you are adding multiple event listeners to the same element.

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So go ahead and try this out.