EasyToggle (Tab Navigation)

Simon Willison has created an easy way to enable tabs in web pages. There is no javascript
coding involved. Just include the .js file and add the class to your links.

I’ve been working on a new inobtrusive DHTML effect: easytoggle,
which is an inobtrusive implementation of the common effect where links or tabs can
be clicked to reveal part of a page while hiding the other parts. It’s similar in
some ways to the Multi
part forms with Javascript
technique.

The idea is pretty simple – all you need are a bunch of links and a bunch of elements
that should be toggled by those links. When adding special behaviour to links it is
always a good idea to ensure that they still link to something sensible, so that in
user agents without Javascript support they still do something useful. In this case,
it makes sense for them to act as anchor links that point to the elements with which
they are associated. With easytoggle, all you need to do is define the links, point
them at an element with an ID and assign them the class ‘toggle’. The script does
the rest of the work. For example, for a simple set with only two panels the markup
would look something like this:

<ul> 
<li><a href="#p1" class="toggle">Panel 1</a></li> 
<li><a href="#p2" class="toggle">Panel 2</a></li> 
</ul> 
<p id="p1">This is panel 1</p> 
<p id="p2">This is panel 2</p> 

That’s all it takes – the demo has
a very slightly more complicated example.

I thought it was finished, until I tested it in Apple’s Safari browser. In Safari,
the worst possible thing happens. The initialisation code which hides all of the panels
after the first one works fine. Unfortunately, the code that causes the links to change
which panel is visible fails silently, leaving only the first panel accessible to
users with that browser. That’s a big problem.

It was at this point that I discovered that Safari’s support for debugging Javascript sucks
rocks
. Firstly, the browser gives no indication that a bug has been encountered.
I’m sure this is a deliberate usability decision, but it also means users who encounter
a bug won’t even know that there is a problem with the site. A quick Google led me
to this
page
, which told me how to enable Javascript error reporting:

  1. In a command line shell, execute defaults write com.apple.Safari
    IncludeDebugMenu 1
    (apparently Safari
    Enhancer
    lets you do this from a GUI).
  2. Reload Safari and check the “Log Javascript Exceptions” option in the
    newly enabled Debug menu.
  3. Start Console.app, which lives in

    /Application/Utilities
    . Note that this is not the same thing as
    the command line console. This took me a few moments to figure out. Macs remain a
    strange new realm of discovery.
  4. Javascript exceptions will now appear in the Console.app window.

Excellent – just what I needed to know. The entire error message I got when I clicked
a link? (event handler):Undefined value. Gee, thanks
a lot Safari. If anyone has any ideas how I can fix the script in Safari (or at the
very least prevent it from being unusable) please leave me a note.

Update: Thanks to a
tip
from David Lindquist, the
updated version of the script
now works in Safari. It’s a little bit uglier though.


[Simon Willison’s
Weblog
]

EasyToggle (Tab Navigation)