javascript 中的条件基于当前显示的页面

Question

because of some problems with joomla "in-content javascript" I have to give all my js logic to one file, but there are problems with inconsistence of dom elements across my site (it is ajax driven, so there is only one script and various DOMs). What is the best solution to make some conditionals solving this problem..

Is it checking $(selector).length , or is there any better solution..

And in case of the $(selector).length , is there a way to save this selector to variable (performance issues) for example some kind of

 var selector = ($(selector).length !== 0) ? this : false ;
 if(selector) { makeSomething; }

The this is actually pointing to Window object..So is there any way to make it like this without need of reselection?

Thanks

Answer 1

var $obj = $('selector');
if ($obj.length) { makeSomething(); }

Actually, this is only meaningful if you are searching for the existence of a certain element (that might identify a whole page) and running several operations based on that.

If you just want to do something on the elements like

 $('selector').append('x');

the condition might be useless, because if the jQuery collection is empty, the methods won't run anyways (as pointed out by @Gary Green ).