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Hello and welcome.

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In this video I will be introducing you to javascript functions.

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Functions are a way of packaging functionality that you wish to reuse.

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So a function basically can refer to a block or a piece of code that is designed to perform a particular

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task.

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Jemas group function is execute it when some theme in it back evil a mean cause it.

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So in order to activate a function after it has been created.

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We need to invoke it or call it.

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And usually you do that by its name.

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Javascript has many built in functions that you can use very low on his alert which enables you to create

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pop up box messages.

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Javascript also enables you to create your own functions and the way you create your functions in Javascript

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is by using the function key word from chao's often takes arguments and arguments are bits of data that

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the functions need in order to perform or do their job.

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And these arguments are placed inside parentheses which are separated by commas.

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If there are more than one argument.

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So inside my console I have created a function and the way you create a function you Busy B have to

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type in the keyword function followed by the name you want to call the function.

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When you create creating function it's very nice to name your functions as close as possible to the

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task that the function is meant to perform.

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See my function I've called it and none which indicates that this function is going to be used to add

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numbers together.

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So when you create a function you have to type in the word function followed by this space then the

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name of the function and then you have to have parent.

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This is sometimes the parentheses can be empty but you must have that in order to create a function.

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And then if you've got any arguments you parse the argument inside the parentheses.

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If there's more than one argument you separate them by a comma.

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You can see here number one.

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Here's an argument not to refer to as an argument.

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And once you specify the arguments if there are any inside the parentheses you have this curly braces

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you call the opening curly braces here and the closing curly braces and inside in between the curly

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braces is the block of code that has to be executed when the function is invoked or called.

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Notice here also caused a return mistake here.

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Basically the return statement tells the browser to return the result variable out of the function so

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it is available to use right.

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This is necessary because variables defined inside functions are only available inside does function.

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This is called variable scope so when you create variables variables can be available try out the application

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or out the scope which is known as global so if you create a variable and you declare it outside the

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function that makes that variable global That means you can use it anywhere within the block of code.

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If you define a variable inside a function like I done here I've defended variable called result and

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I've set that variable result to cause to whatever value is passed as number one and add added to value

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passed as number two.

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So this variable is local to this function so he can only be accessed inside this function so when a

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variable exists inside a function as a function has been executed variable basically is destroyed.

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Or you know it's because on you you can't use it again.

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China has been called that.

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It is served its purpose.

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However if you want the variable to be available you have to use the written statement that way to tell

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the browser to return the result or the variable out of the function so that it is available to use.

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You'll only do this for variables.

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This site defined inside the function then known as a local variable scope so variables defined outside

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of function global.

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So you can access them from anywhere within the US within the javascript code whereas variables defined

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inside function like I have done here referred to as a local scope variable.

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So here I have defined this variable at the nump.

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Now to make or to invoke this function not I have created it.

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All I need to do is call the function his name which is add on and then I have to you must add the parentheses

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and then I'm going to pass it to values because I've got two arguments there.

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So if I see 10 comm. are 20 and I close the parentheses and the press Enter now add 10 and 20 together

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and give me 30.

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All right so any time I want to use this function all I need to do is call the function by his name

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and then pass in two arguments so you can see he sees me having to rewrite the function again.

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I've already written it to find it.

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All I need to do is just call it parsing whatever arguments I need for the functions.

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For example you can create the same page maybe on what application or anything.

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This is just a basic illustration to show you the importance of functions so you can create functions

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for different kinds of task or to do different things.

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But once you've created the function you then have to write the code again or you need to do is just

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call the function by its name parsee whatever arguments you need to do.

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Mike I've passed in here and been at the function execute.

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If I want to pass in more argument I just call the function is the name that passes in C at 6 and 6.

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Now add six the six together.

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It will return 12 because I have already done it in all the functions here.

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So all I need to do is call it base name and pass him arguments so that's basically how you create and

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use function functions are a very powerful concept in javascript.

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I'm only barely scratched the surface here.

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This is just an introduction to Javascript function.

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There's a lot more to it.

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So that's it for this too.

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Thank you for watching and bye for now.