Read boolean HTML attributes with jQuery
Friday, 1 January 2010 @ 13:02After much testing, I have concluded that in order to use jQuery with boolean attributes (and have it work in the big four browsers), the following markup must be used: checked=”checked”.
While browsers except any of the following…
checked checked="" checked="true" checked="1" checked="checked"
…only the last option works with jQuery in all browsers.

Which shouldn’t be entirely surprising as that is the only valid value for the attribute, according to W3C[1].
[1] http://www.w3schools.com/TAGS/tag_input.asp