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So first, a quick summary,

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what do we already know about functions?

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Functions are these constructs which allow us to define code on-demand

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and when Javascript reads our script, it basically goes through the entire script first, finds all

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these function declarations which we added, registers them and then it really starts executing the script

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and we can call our functions as often as we want,

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so we have code which we can execute multiple times from different places in our program.

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You also learned that if you create variables or constants inside of a function, they belong to that function

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because of that block scope thing covered in the last module. Functions can take parameters, also called

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arguments and can return a value, they have to do neither of that and they can take as any parameters

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if you want, if you need them but you can also write functions that neither take parameters nor return

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anything.

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As I mentioned, functions can be called multiple times and of course you typically would pass different

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values for these arguments then because that's the cool thing about a function,

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it's code on-demand and it is able to be dynamic because it can take arguments and the arguments can

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differ from function call to function call,

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so the same function will typically produce different results for different calls because of different

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arguments for example and you can also call functions kind of directly or indirectly, where directly

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was when you called a function by adding parentheses after to function name and indirectly was for example

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the case when you bound or when you attached a function to a button with the help of the add event

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listener call which you saw.

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So that's what we already know,

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now let's see what we can learn about functions.