WEBVTT

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In this video you gotta learn how to use defaults.

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Parameter values in E6 functions.

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So first let's go back to East 5 and see how we manage to use defaults parameters so we gonna create

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a function increment which takes a couple of parameters X and Y then he's going to return x plus y if

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y is available or provided.

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Now if y is not provided we're going to assign the value 1 2 y.

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All right so we're going to return

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x plus y.

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Right.

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But if y is not available we're going to need to return x plus 1.

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So we're gonna check if y is 20 point.

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So if that's the case we can return x plus 1.

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Otherwise we're going to return x plus y like this.

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All right.

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So now if you try

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increments of

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5 it's going to return 6 y is not available.

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So you only use the value 1 if you try increment of 5 and 3 then you gonna get the sum of 5 and 3.

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All right so that's how we used to do to do this in E5 so that looks a little bit laborious.

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Right now it is 6.

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Things are a lot easier now what we can do is create a function

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increment 2.

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You can use a function declaration if you like.

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So now we're we to use an arrow function and we can replace the prime which is inside the parentheses

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right.

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And we are returning x plus y but if y is not available we're gonna use a default value.

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And you can set the default value right here.

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All right.

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So what are we saying here.

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Can they return x must y.

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And if y is not provided then we gonna set it to one.

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So now if you try

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increment 2 of 5 you get 6 increments you 5 and 3 you get 8.

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Okay.

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Now what if you use restructuring structuring so suppose that you've got a function greed which takes

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three off a couple of elements first name and last name and we'll just log

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Hello.

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First they must be like this

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we're using here.

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String rituals

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so destroy

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greets of

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Bill Gates for example and we get Hello.

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Bill Gates No.

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Walt if you want to use a default value for the last thing.

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So suppose that's the last name is not provided.

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So we want to leave this empty right.

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So we just gonna say that's an empty string.

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So if we don't provide the second elements inside the array we just get.

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Hello Bill.

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That's very similar to what we did there right.

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And this is using this structuring let's make things a little bit more complicated this time we're going

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to use this structuring with an objects so let's define a function like that.

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So this function will take an object right with the properties item

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and price

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and quantity.

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So as you know we can reduce this to item price quantity without having to specify the value each time.

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So let's say that this function is just going to log something like

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please pay the price for the number of items.

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So

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the price or the cost is going to be price multiplied by quantity All right.

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And

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I'm going to halve the number of items

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which is the quantity

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and then the item they which is going to be item.

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All right so let's try this function.

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Way

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but it is

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let's say that the price is five

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and quantity five.

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What is their price is one.

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Let's see what we get

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what we seek.

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Let's try again.

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So please pay five or five bananas and let's just add a dollar right there so that we can see five dollars

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instead of five.

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So please pay five dollars for five bananas.

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Perfect.

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So now we want to implement default values for this function.

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So if the item is not provided we want to use a default value but now let's bring them.

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Right.

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So that's how he says the default value inside the objects.

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And the same thing happens with the price.

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So if it's not provided you as you just said that to zero the quantity as well is easy to zero.

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So now let's try again this time

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we will provide an empty object like this and let's see what happens.

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So please pay zero dollars or zero bananas.

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So we use the default values as expected.

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Okay.

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So now what happens if we don't provide any arguments inside our function.

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So what do you think.

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So let's save and see well we get an error very thing here can the structure property item of undefined

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must because our object doesn't exist.

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So it's undefined but it's still trying to find the property item of our objects.

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So to fix this you can set a default value for the whole objects but you see that you're seeing the

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parameter so to do that you set the whole object to a default value which is gonna be an empty object.

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So now the object is going to exist.

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All right.

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It's not gonna be undefined.

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So let's try now and this time it works and we've got our default parameters inside the objects.

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All right.

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Now let's simplify the syntax of our object which is using the problem.

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Since the names of the properties are the same as the variables we're using that we can just delete

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these

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like with

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all right to know when it's safe and make sure that it's still working.

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Perfect.

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All right.

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So this is a very important feature in E6 defaults by misses and it's going to make your programming

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experience almost easier.

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So in the next video we're going to move to arrest parameters.