how to find a name of class from page in jquery

                                    var myVar = $("#start").find('.myClass').val();

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

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

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

                                    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();
    }); 
}