When I should use var function and when function

Question

I know what the difference between these two are:

var myFunction = function(a) { ... }
function myFunction2(a) { ... }

I just can't figure out when I should use the first one and when the second one.

I saw this var functionName = function() {} vs function functionName() {} but as I said, I know what the difference between these two are.

Answer 1

well, the two options have pros and cons as told in the duplicate post. If you use:

var functionOne = function () { … }
function functionTwo () { … }

then functionOne won't exist in the block prior to its definition, and is being defined at runtime. Whereas the other option, functionTwo is defined at parse time and can be called anywhere in the program. Another thing that changes is the behavior of this inside the function.

So basically, your question is:

• how do I want to scope my function?
• if scope does not matter, do I prefer run time or parse time?

To get the full answers to those questions, I really advice you to read and reread the short book from Crockford "Javascript the good parts"‎, and it looks like @wumm's suggested article is pretty relevant as well.