About a code Bootstrap Multilevel Dropdown. FilterSelect is an extremely simple cascading dropdown (aka dependent dropdown) plugin that automatically shows/hides select options depending on the value of other select elements. Activate the plugin by calling the function on the first select element as this: 5. Cascading dropdowns You can add drop-down menus to almost any Bootstrap component using the dropdown plugin. 6. Make bootstrap drop down buttons cascading. You would need an array that would pertain to the country selected. Heres how you can put them to work with either