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Welcome back, my friends, to another lecturer in today's lecture, are we going to talk about S8 or

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ECMAScript 2017?

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So last time we covered S7 in now the time has come to cover these S8 features to the day.

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We're going to talk about a couple of things.

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We got to talk about pets start pet and trailing commas in function parameter lists and calls.

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What a long name for for it will be object values.

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Object entries in object keys.

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Now object is not new, but I didn't never told you about this one, so it's my fault.

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OK, so let's start with this.

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So these are two string methods.

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The first one that start and pattern for that, let's create first.

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Name and let's call it and this guy.

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Counsel, whoops, come on.

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Console dialogue, we're going to cause a lot of the first name right away and let's go back here.

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Let's see what's happening.

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You don't need to see this.

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So and these they're right.

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So we control a lot.

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So what we can do now, I'm just saying console the log and I'm going to see a first name.

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Not bad.

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Come on.

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Bad start.

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And because this is a method we need to use that curly brackets, I'm sorry, not brackets and let's

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say at 15, dear.

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So what you think will happen.

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So there you go.

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The and the is shift to the right for 11 spaces.

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When I say 11, somebody will ask me, Will, there is a 15.

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Well, 15 is our number.

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But you need to also count this Andy character.

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So we have two for so 15 minus four.

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That gives you 11.

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So the 11 characters or 11 spaces will be added to this string.

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And this is good for indentation, right?

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It's a very good for making padding.

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So adding padding to the string on left and on the right.

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So we have this for the left.

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So let me just do it like this.

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Bad stark.

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To add.

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Batting to the left, right, and I'm just going to copy this, but I'm not going to need everything

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here, I don't need Yandi anymore.

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So Pat and yeah, let's say to add padding to the right.

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Off the string.

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But.

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Very good.

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Now, Pat and.

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It's been like this.

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There you go, but you don't see it here, right?

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You don't see it, but if I do this, yeah, you will see it.

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So that's why I can say I can concatenate with DOT there.

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There you go.

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So if I put it here like 10.

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That will move, right?

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So it's adding actually six.

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Right, it's not 10, one, two, three, four, five, six in here was 11, right?

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One, two, three, four, five, six, seven, eight, nine, 10, 11.

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Wow, that was super tired for me.

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I just I didn't expect to be so, so tired for me.

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OK, so we have done this to so bad start and end.

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Now what we need to continue is to use these trailing commas and in function parameter released and

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calls.

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So listen, you don't have to worry about this part and.

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It's not nothing but just a synthetical sure, right.

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So what we can do now?

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I'm going to create a function and we're going to test this inside a function because it's saying,

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whoops, parameter list.

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Right.

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So where we do have parameter list, well, inside a function.

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So const comma function.

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Wow.

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This is the first time that somebody's saying comma function and that is going to be me.

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OK, so I'm going to say A, B, C, D and let's create here a narrow function and cancel the log a,

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B that's it.

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Because of the long and B and call it from here.

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So you're going to say.

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Karma function.

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And just pass one, two, three, four.

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So we have four.

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Yes, we do.

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OK, now I do have back one and two.

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So what's the idea here?

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We trailing commas, in fact, in a function parameter list.

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Let me just copy this one.

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So you know what's happening there.

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Well, imagine if we add here a comma and if we save it, then it will not change the output.

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And why this is useful?

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Well, there are two benefits.

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First, the rearranging of items is very simple because you don't have to add or remove commas if the

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last item changes its position.

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Now, this might confuse to you, but imagine here that we do have like a lot of parameter lists, a

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big one.

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And instead of the in one line what the developers are doing, not me.

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So they're doing this same as we do with objects, right.

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Good.

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So now, instead of thinking about rearranging items and we don't have to remove her at commas at the

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end because you want to move this one on top here, but the comma is going to stay there, right?

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It's not going to mess around with the coat.

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So that is why that is one of these useful benefits.

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It's not much, to be honest.

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The second it helps a version control system with tracking which what actually change.

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So this probably does it make sense right now?

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The last part is that it helps a version control systems with tracking what actually change.

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And I'm going to just show it to you here.

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In common, because we don't need this to run, it's not it's not going to run.

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So here I'm going to say food and we change this.

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From so I'm going to say from two, yeah, two, this is let's hear Essabar, right?

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And but you don't you don't need to think about this too much.

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Right.

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And it's not even something that is pleasant for explaining.

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You're not going to see much.

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But just make sure that even if you put it here, comma, it will not change the apple.

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What will happen if we put a comma here?

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Right.

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There is not going to change up because parameter lists and calls, because this is what we are calling

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a function.

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OK, but it's never a good idea.

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I never put a comma there.

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I'm not going to do that.

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OK, but here you can get a new if you want and you don't have to worry about the commas.

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OK, this was super weird for explanation.

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Nice.

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Forget about this.

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Number three, now we move to number four, a number for a very, very good right object values, object

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entries and object keys.

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I'm going to start with object keys first.

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I'm not going to say four here, but I'm going to say object.

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So why do we need somebody will say, why do we need object keys?

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Well, let's first create one.

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Object call, user object, and inside this user object, we're going to have a couple of user users,

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so user one, right?

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So this will be just thumb.

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Then we're going to have user two.

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It will be Andy.

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Come on, Andy.

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Don't mess with me.

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User three.

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It will be Sarah and user four, it will be Angelina and put a breathing space there, why do you doing

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this?

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Good.

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And there you go.

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Now we have our object now object which is used when we want to loop through this object, as we loop

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through the arrays using the foreach or Matmata, because we used it for each Matmata to other methods

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for arrays.

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But we can't use it on objects in this object.

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This allows us so to that to use that functionality on top of the objects.

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OK, let me show you to this one.

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Now we need to say object keys just like this, and it will change a little bit color because this is

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a reserved word user object.

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We need to pass the entire object here.

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Good.

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Now I'm going to say for each and inside, I do have access to the key.

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What is going to put that one in bracket?

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OK, so if Consul Log.

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And I'm going to say key, and here I'm going to pass the key here, right?

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But that will give me this user one user to user three on each and every loop here.

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But what about the value?

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So these are key value pairs.

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Well, the value we can just get it like this.

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You don't have to type this one if you don't want it.

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But just it's going to make more sense like this.

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So the value we can grab it if you use a user object and we pass the key.

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OK, let's see what this will come up to.

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So this should have their karma.

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Otherwise, it's complaining to us.

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OK, so save it.

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There you go.

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We have key user one value, Tom, key user to value and the user three.

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Sarah four will be Angelena.

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Now, you know how you can loop through objects like they're on the rate and that.

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Object that keys, I'm just going to write this for you guys so you can understand it.

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So it's keys, not key is used when we want to loop through.

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Objects.

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As they are arrested and now, because I don't have enough space, I'm just going to put it here, OK?

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Satisfied?

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Nice.

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What about the number?

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Let me just grab this two number for a number five.

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And number five, so I have a user object values and object entries, so these two features makes our

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life even more easily easier.

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We don't have to do this anymore.

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OK, so what we can do.

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So let's start with user and sorry, object entry.

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So object entries will give back an array from your user object with all the entries you can get.

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OK, let me just show it to you, this one, because it's super confusing, I know, so we need to say

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object and trees in inside, we just plug the user object and we say for each there and I'm just going

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to use the key word entry here.

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You can use whatever you want.

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We already know this things.

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So Konza log the entry and let's see what's happening there.

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Cannot convert undefined null object.

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What's happening here?

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I have no idea.

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So this is happening.

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You should say entry's not something bad.

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Save it.

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There you go.

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Now you have four arrays with two items, four arrays.

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So this will give us back an array from our user object, right.

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So.

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This is actually entries here, not confusing this values there, so this

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will give us an array.

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Of what?

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User object.

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Object key value pairs, because we have different key value pairs here, we have four, right?

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So if we look if we cancel out the object.

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The user object right, there you go, the user object is like this, and now we have one.

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How many here you see property and value you see for then we have a four thou four arrays with two items.

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So that is about the user object entries.

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And now we need object values.

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So the object values will give us the value back of each object property.

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So it's not going to give this key value pair to us.

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It's going to give us just a value.

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Right.

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And that is something where something very useful.

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So I'm going to say object, not values.

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And inside I'm going to plug the user object and I'm going to say for each so I can say value doesn't

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matter what you want to say here.

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If you want to say something else, you can do.

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And I'm going to say Kanza log.

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Value.

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And I don't know why I'm not printing this in one line, it's going to work, right.

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Let's see.

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Very good.

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There you go, I have Dormandy and Angelina.

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Those are the values from the properties, so these so object values will give back the values of the

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object properties.

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These are the properties on the left side and these are the values, key or keys doesn't matter.

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Keys nice.

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There you go.

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Now, you know all of it.

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And I have some very interesting exercises for you.

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Right.

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Make sure that you do them in for the for the previous lecture.

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So we have at Pat Start, Pat End and we have these trailing commas, what you can forget a little bit.

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So in simple words, even if you add comma there, it will not throw you an error.

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That's it.

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Even if you had to come on there and.

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Then we do object that keys so we can lub we can loop through the through the objects, same as we did

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with Arae.

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So we before, if we don't use this, we will not be able to use this for each or Matmata.

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Right.

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Object entries will give us back.

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Properties and values in a Inari in one array in each time will give us back an array, each loop will

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give us back on the ring and the last time object values will give us only the value of the properties

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of the keys on left side.

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Right.

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These from the object.

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OK, so there you go.

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Now you know about S8 feature features and there is a one very big feature that I would talk about in

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the next lecture.

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Make sure you watch this lecture because that lecture, because it will be super, super cool and it

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will be about async awake.

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So that is one of the biggest feature of S8.

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Right.

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And it's built on promises.

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On top of promises, so, yeah, we know what you need to know.

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Promises as well in order to tackle that one.

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So seeing that one and take care.