How to create checkbox inside dropdown?

Question

I want to create a multiple selection dropbox list. Actually I have to select more than one option using a dropdown menu. When I simply do this as shown bellow:

Answer 1

Very simple code with Bootstrap and JQuery without any additionnal javascript code :

HTML :

  
    Dropdown button
  
  

    First checkbox
    Second checkbox
    Third checkbox
  

CSS :

.dropdown-menu label {
  display: block;
}

https://codepen.io/funkycram/pen/joVYBv