Dropdown / select in Angular4

I am working on an AngularFire2 project using Angular 4.2.4 and Angular CLI 1.1.3 and new to TypeScript. In several components I need to use searchable dropdowns / tags as seen here and.

I can't get any of the .js files to run when I reference them in my index.html file like this:

<script src="assets/semantic-ui-dropdown/dropdown.js"></script>

      

        
        
        
      

    

From what I could find it either has to do with the typescript definitions or something is wrong with the way I have included JQuery (only the script tag in index.html). After doing many other threads, I have absolutely no idea how to do this. Do I need to import something into the component? My goal is to use the classes in the html document as Angular 4+ versions of them are not available yet (as far as I know).