function MyClass() {

    var id_nr = Math.ceil(Math.random() * 999999);

    this.button_id = 'button_' + id_nr;

}

​

​

MyClass.prototype = {

    createButton: function() {

        var msg = 'Button \'' + this.button_id + '\' was clicked';

​

        var my_button = $('<input>')

                .prop('type', 'button')

                .prop('id', this.button_id)

                .val('Click Me')

                .on('click', function () { alert(msg) } );

​

        $('body').append(my_button);

    }

};

​

​

window.onload = function() {

    var s = new MyClass();

    s.createButton();

    var w = new MyClass();

    w.createButton();

};