What is the difference between these two functions/approaches?

Question

I use only jQuery for writing JavaScript code. One thing that confuses me is these two approaches of writing functions,

First approach

Answer 1

function myFunction() {}

...is called a "function declaration".

var myFunction = function() {};

...is called a "function expression".

They're very similar; however:

• The function declaration can be declared after it is referenced, whereas the function expression must be declared before it is referenced:

  // OK
  myFunction();
  function myFunction() {}
  
  // Error
  myFunction();
  var myFunction = function() {};
  

• Since a function expression is a statement, it should be followed by a semi-colon.

See Function constructor vs. function declaration vs. function expression at the Mozilla Developer Centre for more information.