How to add click event by class name?

Answer 1

Optimize your code by not using live() as we cannot stop propagation of live() events

Use on() (jQuery 1.7+) or delegate() (below 1.7)

Most efficient solution for your scenario in this case would be:

//  $('.mmenu').on("click", ".menu_button", function() {   // jQuery 1.7 & up
    $('.mmenu').delegate(".menu_button", "click", function() {
        var id = $(this).attr('id') // or this.id
        if ( id == "m1" ) {
            // ..code
        }
    });

In this way, you have only one click event bound to the main div $('.mmenu'), which will also work if you add elements (new li with divs) in the future