Answers for "jquery checkbox if check"

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.

jquery check if checkbox is checked

if($('#on_or_off_checkbox').is(':checked')){
    //I am checked
}