Answers for "jquery when checkbox checked"

jquery set checkbox checked

//jQuery 1.6+ use
$('.checkbox').prop('checked', true);
//jQuery 1.5.x and below use
$('.checkbox').attr('checked', true);

jquery if checkbox checked

$( "SELECTOR" ).attr( "checked" )  // Returns ‘true’ if present on the element, returns undefined if not present
$( "SELECTOR" ).prop( "checked" ) // Returns true if checked, false if unchecked.
$( "SELECTOR" ).is( ":checked" ) // Returns true if checked, false if unchecked.

checkbox is checked jquery

$(your_checkbox).is(':checked');