how to find all the class demo in body in jauery code example

Example 1: get all classes of element jquery

var classList = $('#divId').attr('class').split(/\s+/);
$.each(classList, function(index, item) {
    if (item === 'someClass') {
        //do something
    }
});

Example 2: how to find a name of class from page in jquery

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();
    }); 
}