Custom tag box widget based on jQuery select2


<!DOCTYPE html>
<html>

<head>
    <title>Welcome to JQuery</title>
    <script src="https://unpkg.com/jquery"></script>
    
    <script src="https://surveyjs.azureedge.net/0.12.17/survey.jquery.js"></script>
    
    
    <script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/js/select2.min.js"></script>
    <link href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.3/css/select2.min.css" rel="stylesheet" />
    <link rel="stylesheet" href="https://unpkg.com/bootstrap@3.3.7/dist/css/bootstrap.min.css">
    <link rel="stylesheet" href="./index.css">
</head>

<body>
    <div id="surveyElement"></div>
    <div id="surveyResult"></div>
    <script src="./index.js"></script>
</body>

</html>


Survey.Survey.cssType = "bootstrap";
Survey.defaultBootstrapCss.navigationButton = "btn btn-green";

Survey.JsonObject.metaData.addProperty("dropdown", {name: "renderAs", default: "standard", choices: ["standard", "select2tagbox"]});
Survey.JsonObject.metaData.addProperty("dropdown", {name: "maximumSelectionLength", default: undefined});

window.survey = new Survey.Model({ 
    questions: [{ 
        type: "dropdown", renderAs: "select2tagbox", maximumSelectionLength: 2, choicesByUrl: { url: "https://restcountries.eu/rest/v1/all" },
        name: "countries", title: "Please select all countries you have been for the last 3 years."
    }]
 });
survey.onComplete.add(function(result) {
	document.querySelector('#surveyResult').innerHTML = "result: " + JSON.stringify(result.data);
});


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({
            theme: "classic",
            maximumSelectionLength: question.maximumSelectionLength
        });
        $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({maximumSelectionLength: question.maximumSelectionLength, 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;
        question.choicesChangedCallback();
        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
});


.btn-green {
  background-color: #1ab394;
  color: #fff;
  border-radius: 3px;
}

.btn-green:hover, .btn-green:focus {
    background-color: #18a689;
    color: #fff;
}

.panel-footer {
    text-align: right;
    background-color: #fff;
}