It appears that in Firefox, if you create a td and set its rowspan to some value when there are no rows for it to expand into, the attribute will be completely ignored, even if you add rows afterwards! Needless to say, this is very annoying. The solution? Build your table backwards.

The code I have now is something like this (note that I’m developing using the Mootools framework):

var tbl = new Element('table');
var trs = new Array();

for (var i = 0; i < 4; i++) {
  var tr = new Element('tr');
  tr.grab(new Element('td', {
    'html': 'Cell ' + i
  }));
  if (i % 2 == 0) {
    tr.grab(new Element('td', {
      'rowspan': 2,
      'html': 'Span ' + (i / 2)
    }));
  }
  trs.push(tr);
}

for (var i = trs.length - 1; i >= 0; i--) {
  tbl.grab(trs[i], 'top');
}

What does this code do? Well basically, we’re creating a table with ten rows and two columns; the cells in the right-hand column each occupy two rows. The result will be something like this:

There are many, many workarounds which provide this functionality, using such tricks as hidden input elements, global onclick handlers, and so on, but the simplest is simply this: give your div a tabIndex attribute. For example,

works perfectly in Firefox, Internet Explorer, and Chrome as shown in the example below:

The value of tabIndex can have significance, too:

• -1: The user can’t tab to the element, but it can be given focus programmatically (element.focus()) or by being clicked on.
• 0: The user can tab to the element, and its order in the tabbing is automatically determined.
• >0: Give the element a priority, with ’1′ being the highest priority.

I originally discovered this technique on this CodingForums.com thread.

• Firefox
• Internet Explorer
• Google Chrome

• Safari