Rails spinoffs - May 2007 - Finding the Focused Element of a Form

Finding the focused element of a form is something that I''ve run into a
few times and usually, I''ve use an onFocus event to set a variable 
somewhere within an accessible name space which could be checked, but 
while effective, it always seemed like it should be a part of form and 
not a random variable.  So, I hacked around and came up with this 
solution.  First, some code:

Form.getElements($("some_form")).invoke("observe",
"focus",
function(event) {
    var focused_element = 
Form.getElements($("some_form")).find(function(e) { return e.focused
==
true; });
    if(!focused_element) 
Form.getElements($("some_form")).each(function(el) { el.focused =
false; });
    else focused_element.focused = false;
    Event.element(event).focused = true;
} Form.focusFirstElement($("some_form"));

The above code will first try to find a focused element.  if it can''t, 
it will add a focused property to all elements of the form and set it to 
false.  Otherwise, it''ll unset the focused flag for the element that it
finds.  Finally, it sets the focused flag for the element which spawned 
the event to true.  The first line of the anonymous function can then be 
used later to find the focused element.  I also use the 
Form.focusFirstElement() function to automatically make sure that the 
system will (obviously) focus the first element but (perhaps less 
obviously) also create a focus event for the element which triggers the 
setup of all the code above.

The code seems pretty compact and it''s very effective.  I
haven''t looked
up yet to confirm if the Form.getElements function returns extended 
elements or not, so IE might be a problem with this specific 
implementation.  But more that the nitty gritty of browser concerns, I 
wonder if anyone has a better way? 

  - Dash -



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