I am currently fixing one bug at work and found an interesting problem.
Something works in IE but doesn’t work on Firefox and Chrome.
After some debugging I found the problem
<span id="someSpan" value="some value">some caption</span>
var value = $('#someSpan').val();
This works only in IE. In Firefox and Chrome it returns null.
According to documentation jQuery .val() function makes sense mostly for form elements and it just checks elem.value property, but this property is set only in IE.
So the fix is
var value = $('#someSpan').attr('value');