Where is the For Next in the function

[Claus Mygind]

I am having some trouble understanding the syntax in an anonymous function.

I understand that a for next loop is constructed like this

for (var i = 0  i < someNumber  i++)
{
  code in here get repeated for each time in loop
}
 

So the curly brackets defines the start and end of code that is repeated each time through the loop.

What I don't get is where is the start and end of the loop in this example

google.maps.event.addListener(marker, 'click', function() {
  marker.setMap(null);
  for (var i = 0, I = markers.length; i < I && markers[i] != marker; ++i);
    markers.splice(i, 1);
    path.removeAt(i);
}
);
 

There are curly brackets that define the anonymous function, but where are the curly brackets for the for/next loop?

I am trying to construct my own event listner like this:

google.maps.event.addListener(marker, 'rightclick', function() {
  for (var i = 0, I = markers.length; i < I && markers[i] != marker; ++i);
    thisMarkerNum = i;
  (document.getElementById("propertyTable").style.visibility == "hidden" ) ? showPropTable(marker, "boundry marker "+marker.title, thisMarkerNum):hidePropTable();
});
 

I want to capture i and send it as a parameter. Is my if statement part of the loop or what? And why don't we use curly brackets for the for/next loop?

[Plater]

I believe this line:

for (var i = 0, I = markers.length; i < I && markers[i] != marker; ++i); 
 

is the same as

for (var i = 0, I = markers.length; i < I && markers[i] != marker; ++i)
{
}
 

[Claus Mygind]

Yep! I gather that. but the curly brackets denote a start and a finish to the code within the loop. I don't get how the one without the brackets even works and does not throw an error.

[Plater]

Well this statement is completely normal syntax:

if (a==b)
   alert('Values are the same!');
 

and is the same as

if (a==b)
{
   alert('Values are the same!');
}
 

The {} just denotes a grouping of code (it is more complex then that, but basically)

[Claus Mygind]

So in this example

 google.maps.event.addListener(marker, 'click', function() {
   marker.setMap(null);
   for (var i = 0, I = markers.length; i < I && markers[i] != marker; ++i);
     markers.splice(i, 1);
     path.removeAt(i);
 });
 

would we assume only the first line is part of the loop or are both lines part of the loop.

Or is it just bad code and should really be enclosed in the { }

[Plater]

Hmm, with that semi colon at the end i would have assumed NONE of them are part of the loop

[Claus Mygind]

Ok I will have to investigate that further that makes sense even though it does not seem proper to write a for next loop without the curly brackets.

Thanks for the reply

[Dormilich]

maybe it’s just a typo and they meant { instead of ;

[Claus Mygind]

That would leave the leading { missing

[Claus Mygind]

sorry meant the } missing. gotta go in pairs

[Dormilich]

otherwise it would have thrown an error.

[gits]

the shown construct could make sense

for (var i = 0, I = markers.length; i < I && markers[i] != marker; ++i);

as we could notice it increments the counter-variable i from 0 until it finds the marker in the markers-array ... so it seems to be used to gather the index of the marker(-object) in the markers-array - probably for the splice-operation later on. basically it is a proper construct.

kind regards,
gits