jquery get class name

//jQuery get class name of element 
var className=$('#myElementID').attr('class');

var className = $('#sidebar').attr('class');

if ($('.Mandatory').length > 0) {
  //do your thing
}

if ($(".Mandatory").length > 0) {
    // Do stuff with $(".Mandatory")
    $(".Mandatory").each(function() {
        // "this" points to current item in looping through all elements with
        // class="Mandatory"
        $(this).doSomejQueryWithElement();
    }); 
}

$('.Mandatory').each(function(){
  //do your thing
});

$("input[type='submit']").click(function() {
    if ($(".Mandatory").length > 0) {
        // Do some code here
    }
});