Jquery : Even if the checkbox is checked, it is always returning false -

$("td.chkboxalarm", this).is(':checked') 

even if checkbox checked, statement returning false.

chkboxalarm: class each check box in table.

you selecting td elements, not input elements.

you should change to

$("input.chkboxalarm", this).is(':checked') 

or, if chkboxalarm class applied td,

$(".chkboxalarm input", this).is(':checked')