Jquery изберете квадратчетата за отметка

//using plane javascript 
if(document.getElementById('on_or_off_checkbox').checked) {
    //I am checked
} 

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

$('#checkbox_id:checked').val();
//if checkbox is selected than gets its value

$("input:checked")

if($("#rule").is(":checked")){
    $("#form").submit();
 }

var values = $('input[name=grepperRocks]:checked')
               .map(() => { return this.value }).get();

var selected = [];
$('#checkboxes input:checked').each(function() {
    selected.push($(this).attr('name'));
});