[Javascript] finding an element in the DOM sea

Mon Jan 30 22:58:56 CST 2006

OK. This is getting interesting. Two questions, if you please:

1. I can get elements by ID or by TagName. Can I retrieve them by
Class. I tried but couldn't get it.

2. Obviously I have fallen (in a short time really: can't be more than
3-4 years) into, as you put it, the _old_ school. Is there a text(s)
that you could recommend that would put me up to speed again?

Thanks again, and sorry about the Gmail carriage return stripping. I
asked on their forum but haven't ever got a response - guess no one
knows.

On 1/30/06, Paul Novitski <paul at novitskisoftware.com> wrote:
> At 07:10 PM 1/30/2006, Jonathan Gold wrote:
> >Thanks Paul, that is very helpful. But I am still uncertain _what_
> >to call things on the page. Really, I just want to know how to
> >address certain elements. I want the span elements in this case, to
> >allow their background color to be changed to conform to the rest of
> >the webpage. I can view the DOM of my page using the FF extension
> >DOM Inspector. And I find that the node of my span element is named
> >SPAN and that its parent element is called LI and its parent element
> >is called UL, then BODY, then HTML, then something called #document.
> >When I wanted to adjust the background color of the page as a whole,
> >I simply wrote "document.bgColor = myColor". myColor was a variable
> >that had already been set as a hex representation of a color. Now I
> >want to set the background of the span elements to conform. I know
> >this doesn't work, but just to show what it is I am trying to do,
> >here's a line I tried:  "document.html.body.ul.li.span.bgColor =
> >myColor;" So my question is: how do I correctly address Mr. Span so
> >that he will feel moved to respond to my requests? :~)
>
>
> Hmm.
>
> [I didn't know that document.bgColor was legal, but I guess it's
> assuming you mean document.body.bgColor.]  I figure you can get away
> with document.body.bgColor because there's only one body tag in a
> document, but it's an old-school method of referring to objects in
> the DOM and I recommend you use getElementById() or
> getElementsByTagName() instead.  I wouldn't expect
> document.html.body.ul.li.span.bgColor to work primarily because those
> aren't unique elements in the document (which ul? which li? which span?).
>
> [Rather than using the bgColor attribute, I would recommend using
> style.backgroundColor so that it integrates more smoothly into your
> use of stylesheets.]
>
> Here are some ways of referring to a particular element:
>
> - by unique tagName:
>          <body>
>          document.body.style.backgroundColor = "#FFF";
>
> - by tagName array:
>          <form action=...>
>          document.forms[0].onsubmit = fnDoSomething;
>          (you can't refer to all tags as arrays)
>
> - by id:
>          <span id="span123">
>          var oSpan = document.getElementById("span123");
>          oSpan.style.backgroundColor = "#FFF";
>
> - by object in the DOM:
>          <span>
>          var aSpans = document.getElementsByTagName("SPAN");
>          aSpans[x].style.backgroundColor = "#FFF";
>          ...where x = 0-N in the array of span elements in the document
>
> So my earlier example of how to walk the DOM was precisely what you
> want to do (whether you know it or not): generating an array of
> objects you can cycle through to point to each individual span.
>
> Clear as mud?
>
> Paul
>
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--
Jonathan
Berkeley, CA
http://home.pacbell.net/jonnygee/