Webmaster Forum / HTML, CSS, Scripts / JavaScript / June 2007

There is no difference at all. Both create a variable
called saveFinal which is a pointer to that function.

Historically, the first example came first. I'm not
sure at what point (but it was in the 90's) that the
second format became valid.

~dd

Always declare variables (use var):

var saveFinal = ...

The difference between the two is when the function is created.  The
first example is a function declaration, so it will be created when
identifiers are resolved and before any code is executed.  The second
is a function expression, so the identifier saveFinal will be created
up front (provided var is used) but the function itself won't be
created until the code is executed.

The result is that you can place the code that calls a declared
function before the code that declares it, you can't do that with a
function expression, e.g.

 // This is OK
 x();
 function x() {...}

 //This isn't
 y();  // --> error
 var y = function(){...}

Function expressions are frequently used inconjunction with an object
to create a namespace, e.g.

 var rX = {};
 rX.funcA = function () {...};
 rX.funcB = function () {...};

or

 var rX = {
   funcA: function(){...},
   funcb: function(){...}
 }

or

 var rX = (function(){
   // private variables go here
   return {
     // public variables go here
     funcA: function(){...},
     funcb: function(){...}
   }
 })();

and so on.  The above add just one variable to the global namespace
(rX), lots of other stuff can be added and not have any clashes
provided rX is OK.  It makes the library work well with others -
libraries like jQuery follow this model and (can) add just a single
namespace object (jQuery).  Libraries like Prototype.js follow the
model too but create a number of namespaces and so have more chance of
name clashes (which is borne out in practice).

This technique does not make your code object oriented, it just means
you are using  an object to create a namespace.

--
Rob