fstdropdown initializes on page load, just add class "fstdropdown-select" to your select. If you add your select dynamically, add "fstdropdown-select" class to it and call function setFstDropdown(). If you change your select options list, use document.querySelector("your select").fstdropdown.rebind() to update dropdown list. You can use multiselect, by adding attribute multiple="multiple" to select. If you dont need search in dropdown, just add data-searchdisable="true" to the select. To add placeholder to search input, add data-placeholder to select. To use opened select or multiselect, add data-opened="true" to select.