Question

So the have seem something like this today:

$$('input').each(function() {
 // do something
});

What is the difference between that and this:

$$('input').each( // do something );

The private function on the first example is within that for loop scope, so it is not reference-able anywhere else, so what would the benefit of having it?

Answer 1

The anonymous function knows its current scope and variables.

function a() {
   var foo = 'test';
   $('something').each(function() {
      alert(foo);
   })
}

This function would alert ‘test’ because foo is defined within its scope.

function a() {
   var foo = 'test';
   $('something').each(b)
}

function b() {
   alert(foo);
}

This function would cause a javascript error stating that the variable foo is undefined.

If you need to define a function that only makes sense within an exact scope and don’t want to throw lots of variables around or recalculate a lot of things, it’s more comfortable to define an anonymous function.