how to detect if there is checked checkbox or not in jquery code example

Example 1: How to check whether a checkbox is checked in jQuery?

//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
}

Example 2: how get checkbox if checked in jquery

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