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For that let's just play around with javascript and I'm in a brand new empty folder which I opened with

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my IDE, visual studio code and in there, I'll create a new file and I'll name it play.js, the name is totally

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up to you though.

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Now let me start with some core language features, variables and functions

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and again you should definitely dive into a core javascript resource like the ones I linked in the second

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lecture of this module

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if you are brand new to Javascript,

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so I by now do expect you to know what variables functions are, I also expect you to be aware of what if statements

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or loops are,

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these are all core things you got to have set by now because they are crucial for javascript no matter

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if you are using it in the browser or on the server.

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So for variables, you might know this syntax with the var keyword,

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you can have var name and for example store Max in there, right.

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This would be a variable and now you can use that for example to simply output it like this

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and if we now run this file with nodejs by running node play.js, this is the command we have to

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write in the terminal, navigate it into that project folder, so into that folder where I'm having this play.js

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file, then I see Max down there, right

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so that is some Javascript code.

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We can also create another variable, age which now would be a number,

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it's not enclosed in quotation marks, so this first one is a so-called string,

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this is a number,

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we can also add a third one, hasHobbies and that would now be a boolean,

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these are some core types

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Javascript knows. 

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True false are booleans, numbers are well numbers,

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they can also have decimal places,

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these are strings. 

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And now here I can also define a function with the function keyword summariseUser,

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this is how you create a function in javascript and there, we could return something,

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functions can return values with the return statement,

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they all can get input like user name, user age and user has hobby, you can name these arguments as these

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things here are called,

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however you want.

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These are now local variables only available inside of the function, not outside of it

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and then you can return

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name is plus user name plus let's say some text with a comma, a whitespace, age is whitespace, user age

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plus and user has hobbies and then user has hobby, something like that.

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Now here I am simply returning some text which I manually concatenating by a hardcoded strings and the

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dynamic values I'm getting as an argument.

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Now we can also console log the result of summariseUser and we call a function by adding parentheses after the 

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name

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and now we just have to pass in data we expect here as arguments, so we need to pass in three arguments

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here, the name, the age and has hobbies, so the three variables

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I defined up here. We could have directly accessed them in the function too by the way,

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we don't have to take the way of accepting arguments but this is a pure function which does not depend

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on anything from outside the function but gets all the data it works with as part of the arguments which

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is a nice way of writing functions.

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And now if I execute this, well then we get this output here.

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Now this is just a summary of the features you should be aware of

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as I mentioned, I just want you to know or I just want to be sure that you know how we work with variables,

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how we would work with functions, how we call functions

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and that you understand how parameters or arguments in the function are used in there and only in there,

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we couldn't use user name outside of there because of something called scoping in javascript, 

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we can then call a function like this and pass in the data,

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we could hardcode the data here or refer to variables which have to be available in the scope of this statement

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which is the case for these variables since they are global variables and these are variables and functions

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and how we interact

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and these are some core of features you have to be aware of.

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Let's now dive into something more exciting in the next lecture.