Hello, in this JavaScript video, I am going to show you functions also known as methods. So what is a function, it essentially allows you to bundle up some code or you know, also known as abstract any out, and you assign some name to it, which is the function name, you call a function. And what we've done here would prompt prompt built in, and you know, console dot log as well for that matter. And you'll perform those, you know, instruction, the set of code. So if you have 10 lines of code in there you call a function, you'll initiate those 10 lines of code, am I thinking, why do I want to do that sound like you know, expert, main reason is, when you are creating application, you are going to have functionality that's used a lot throughout the different parts in your application. And what will happen is the actual code is the same and you'll just be duplicating it.

If you need to update it, or let's say fix a bug. You have to do that in every scenario. Imagine if you have the same code as 50 lines of code in 100 different locations. And trust me that is more than possible in any half decent size application. So anything beyond what you know, just the simple stuff we're doing here with a few lines, you'll have duplicate code unless you use functions. So let's just go ahead and create one, get rid of this.

So to create one, you just put the keyword function, then you name your function, I'm going to name it awesome funk, and open curly brackets, curly braces, and in here is where you specify all your code. And I'm going to specify two lines. And I'm simply going to do a console log. And these console logs are gonna say hello. I was already gonna do the one. We're gonna do hello world.

I'm gonna do hello and goodbye. So if I refresh I didn't see Nothing is printed out. My thinking was that we got the three console log lines, there's no errors produced. We've used console before, what's going on. And the thing is, they've been encapsulated in this awesome funk member that prompt function that we used in the previous video. If you don't initiate a call that function, if you know the prompt box doesn't appear, you don't want you know, everything just appearing and happening without you initiating it.

But to initiate it, you just use the name of the function, the awesome func open curly brackets and a colon. And this because it doesn't have the keyword function, it says find a function call some function, he knows is a function because of the curly braces. And it's, you know, it's going to locate it and click it. There you go. It is working awesome stuff. So we can do a couple of other things with functions.

One, we can have values passed in To the function, so let's create for like an adder function call itself, you know, that's the mathematical term for it, function sum. And we want to pass in two values for these two value, you get like prompt boxes, you could get from the user, you know, using a natural input box, it doesn't really matter how you get them. And in here, we want to pass in two values. So we just go right here, we do ball. And we specify the actual functions themselves. So we just need to specify the actual variable names.

And these variable names are just specific to the function, but you don't need the keyword var sorry, Tom's gonna actually call them num one, comma, num, two. And these are variables and he knows the variables included within the brackets. So that's really nice. Especially By the keyword variable, Okay, number one, number two, you can pass in as many of you wanting to separate it with a comma. They can be all different data types. You want to do number one, so we're actually going to create a variable inside of the var equals, so var result equals number two.

And if you haven't resolved, so there we go. It says not a number. Not a number. That is because we have not passed in anything that we need to pass something invalid passing four and seven. Sure we can handle that or do we need to open the calculator? Let's open the calculator.

Think I'm unable to calculate that four plus seven, because seems legit to me. Nothing all my years do math. I think that's right. So four plus seven is 11. Make sure that is saved. Refresh and we have the value 11 point out.

So that's all great. You might be thinking, what I can just add this so this is you know, glow hierro Are you thinking, Okay, this is really cool we can pass variables in, we could add them, multiply them know, get something from a database, it doesn't really matter what you're doing with it to do something, but why if you don't want to, you know, console log every time. So, maybe you want to get some value put into a variable sign into a variable or console log it or put it into a database or you know this or that or that and how do you do that is called a return type. So if I create another function called sum, and I want to call him return, return, the call wherever you want the number one note to bear in mind, though these are named the same, they are separate variables.

These have a scope of this function, so they cannot be used outside. Same will result result cannot be used outside of this function. If this variable was created outside of the function, and he used the inside, that is fine, we can declare it using the wall keyword inside of the function and expect to use the side. So in here, we are basically going to do the same thing but we're not going to console log it, you use the return keyword, specify what you want to return for the data within colon. And now if I do return the equality should get same value five and nine. That should get us to carry the one square root the two I think we're getting roughly 14 in my head and then we reload.

Okay, nothing has changed. The reason is it literally just a sub consent cola. I will prove that it's simply doesn't print that because we haven't specified, this returns the value. And this is the same thing as writing 14, which does nothing. But we can actually print it out. So if we do console dot log, printed out like so.

There we go, we got 14 printed out. Imagine that is really cool you anywhere that you can put like any sort of data, you could specify a function call. And any data that was turned, you're literally put here. Another thing you can do is to create a variable called epic var, because it is an epic variable, you can make it equal to the result of a function, they return. So if I put in two and 100, quite a large value. And now if I do console dot log, epic law if I save that Go back and refresh it.

There we go. We have printers to print today. So that's function that's really all there is to it. You can put literally any piece of JavaScript code that you want inside of one of them. But these are the main types of function, one without parameters or arguments, one with parameters, and one with parameters that also returns a value. You could also have a function that takes in no parameters, but returns a value.

But other than that the left they do all of this console login as an extra task on I'm going to leave that to you. If you have any questions, feel free to drop me a message. And as usual, I look forward to seeing you in the next video.