Select2 Tag Box

Source code: Survey setup
Survey.defaultBootstrapCss.navigationButton = "btn btn-primary";
Survey.Survey.cssType = "bootstrap";
Survey.JsonObject.metaData.addProperty("dropdown", {name: "renderAs", default: "standard", choices: ["standard", "select2tagbox"]});
var survey = new Survey.Model({ questions: [
 { type: "dropdown", renderAs: "select2tagbox", choicesByUrl: { url: "https://restcountries.eu/rest/v1/all" }, name: "countries", title: "Please select all countries you have been for the last 3 years."}
 ]});


var widget = {
    name: "select2tagbox",
    htmlTemplate: "<select multiple='multiple' style='width: 100%;'></select>",
    isFit : function(question) { return question["renderAs"] === 'select2tagbox'; },
    afterRender: function(question, el) {

        var $el = $(el).find("select");

        var widget = $el.select2({
            tags: "true",
            theme: "classic"
        });
        $el.on('select2:unselect', function (e) {
            var index = (question.value || []).indexOf(e.params.data.id);
            if(index !== -1) {
                var val = question.value;
                val.splice(index, 1);
                question.value = val;
            }
        });
        question.choicesChangedCallback = function() {
            $el.select2({data: question.visibleChoices.map(function(choice) { return { id: choice.value, text: choice.text }; })});
        }
        $el.on('select2:select', function (e) {
            question.value = (question.value || []).concat(e.params.data.id);
        });
        var updateHandler = function() {
            $el.val(question.value).trigger("change");
        };
        question.valueChangedCallback = updateHandler;
        updateHandler();
    }
    
        ,
        willUnmount: function(question, el) {
            var $select = $(el).find("select").select2();
            $select.each(function(i,item){
              $(item).select2("destroy");
            });
        } 
    
}
Survey.CustomWidgetCollection.Instance.addCustomWidget(widget);
survey.data = { countries: ["Andorra"] };


$("#surveyElement").Survey({
    model: survey
});