JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://kendo.cdn.telerik.com/2015.3.930/js/kendo.all.min.js"></script>
<link rel="stylesheet" href="https://kendo.cdn.telerik.com/2015.3.930/styles/kendo.common.min.css">
<link rel="stylesheet" href="https://cdn.kendostatic.com/2015.3.930/styles/kendo.default.min.css">
<select id="parsingmultiselect" multiple="multiple" style="width: 300px"></select>

JavaScript

(function ($) {

  var kendo = window.kendo,
      ui = kendo.ui,
      MultiSelect = ui.MultiSelect,
      CHANGE = "change",
      PASTE = "paste";

  var ParsingMultiSelect = MultiSelect.extend({

    init: function (element, options) {
      var that = this;

      // Base call to MultiSelect to initialize ParsingMultiSelect
      MultiSelect.fn.init.call(that, element, options);

      that.input.on(PASTE, that, that._paste);
    },

    options: {
      // Assigns the name as it should appear off the kendo namespace (i.e. kendo.ui.ParsingMultiSelect).
      // The jQuery plugin would be jQuery.fn.kendoParsingMultiSelect
      name: "ParsingMultiSelect"
    },

    events: [
      PASTE
    ],

    _paste: function (e) {
      alert("data pasted!");
      var parsingMultiSelect = e.data,
          dataValueField = parsingMultiSelect.options.dataValueField,
          parsingMultiSelectDataSource = parsingMultiSelect.dataSource,
          pastedData = e.originalEvent.clipboardData.getData('text'),
          validValues = [];

      multiSelect._close();

      parsingMultiSelectDataSource.fetch().done(function () {
        var dataSourceData = parsingMultiSelectDataSource.data();
        var dataSourceValues = [];

        if (dataSourceData instanceof kendo.data.ObservableArray) {
          dataSourceValues = dataSourceData.map(function (arrayElement, index) {
            return arrayElement[dataValueField];
          });
        }

        // Convert all commas to a single space then reduce all whitespace (and consecutive)
        // characters in the pasted input to a single space to get ready for splitting
        pastedData = pastedData.replace(/,/g, "").replace(/\s\s+/g, " ").trim();

        pastedValues = pastedData.split(" ");

        // Loop through the values pasted in.  If any exist in the dataSource, push them to
        // the array of valid values.
        $.each(pastedValues, function (index, value) {
          if...