[Javascript] See if item is hidden...

[Paul Novitski]

At 01:33 PM 6/22/2004, jsWalter wrote:
>1) I really won't know how far down my Pa21 might be.
>    (Yes, another of Walters "generic" code pieces)
>
>2) its ancestor would be turned off by JS via a code switch
>    but then again, its default state (via CSS) could have it "off"


1) It's easy to walk up the DOM tree looking for a parent, as long as you 
know when you've found it.  You could look for a tag name or, better yet, 
an id or classname (so you can mess with your tags later on and not have it 
break).

I'll assume that your function is triggered from within the span:

<div class="Grandma">
         <p>
                 <!-- any number of levels here -->
                         <span onclick="DoSomething(this)">...

function DoSomething(argItem)
{
         // begin with the chosen item
         oObj = argItem

         // look for the desired ancestor
         while (oObj.className != "Grandma")
         {
                 // walk up one level
                 oObj = oObj.parentElement
         }

         // check visibility by whatever method you like
         if (oObj.style.visibility != "hidden") ...
         if (oObj.style.display != "none") ...
         if (oObj.className != "cssHiddenThing") ...
}

As I understand it, testing the value of oObj.style.whatever will test for 
attributes applied with either HTML or JavaScript:

         <div style="whatever: itis;">
or:
         oObj.style.whatever = "itis"

but will not detect attributes applied with CSS:

         div {whatever: itis;}

In order to do that, you'd need to parse the stylesheet tree, discover 
which CSS selectors applied to your object, follow all the rules of 
cascading, etc.

It would be much easier simply to load up your page KNOWING how things are, 
set them differently if desired with Javascript, and work from there.

Paul