Bootstrap 4 multiselect dropdown

Because the bootstrap-select is a Bootstrap component and therefore you need to include it in your code as you did for your V3 NOTE: this component only works in bootstrap-4 since version 1.13.0 $(‘select’).selectpicker(); <link rel=”stylesheet” href=”https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css”> <link rel=”stylesheet” href=”https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.13.1/css/bootstrap-select.css” /> <script src=”https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js”></script> <script src=”https://stackpath.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.bundle.min.js”></script> <script src=”https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.13.1/js/bootstrap-select.min.js”></script> <select class=”selectpicker” multiple data-live-search=”true”> <option>Mustard</option> <option>Ketchup</option> <option>Relish</option> </select>