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Well if you compare both, we have the function declaration, function statement which look like this and

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the function expression like this which I just showed you.

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Of course needless to say, in function expression form here, you can also still take arguments and still

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return values that didn't change.

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Now the important difference to what it really boils down here is that for this function declaration,

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function statement syntax, Javascript automatically hoists the function to the top and then also fully

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initializes it for you.

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So what I mentioned, Javascript reads the file and no matter where you defined your function, it acts as

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if it would be defined at the top of the file, which means you can actually call functions before you

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declare them.

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That can be convenient and if your code style is to always have the functions at the end of the file,

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then you have to use this approach. With function expressions, this hoisting is also working but the constant

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gets hoisted but it gets hoisted as undefined,

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something I also had a look at in this behind the scenes module.

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So it's basically not initialized so you can't call the function before you defined it and that's an

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important difference,

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you have to define, you have to initialize your functions before you try calling them

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and in my opinion this is a bit of a cleaner style, though you will find both code styles,

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I will say that, it's not strictly bad or worse than the other.

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I personally prefer this approach a little bit,

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I think being forced to define functions before you use them is a great thing but of course it's needless

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to say that you could also simply define functions with the left approach before you use them. So

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you don't have to use the right approach just because you want to do that, the right approach just forces

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you to define functions before you call them. Now

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ultimately it's therefore up to you which one you prefer,

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I am personally a fan of the right approach but as I said, both works and both can be used,

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there is no bad approach here.

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Just to also quickly demonstrate what I meant,

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here we have this function defined.

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Now if I would call start here before that definition, if I save that and reload, I get an error that

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we cannot access start before initialization and we wouldn't get that error

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if I had my function started let's say like that,

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so in this declaration, in this statement syntax. If I would do that,

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this would work just fine as I mentioned because Javascript reads the entire file and if it finds function

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declarations like this, it kind of acts like they were at the top of the file.

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So that is an important difference,

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as I mentioned this is the style

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I prefer but not a style you absolutely have to use necessarily.