JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.1/knockout-debug.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/jqueryui/1.12.1/jquery-ui.css">
<input type="text" data-bind="autoComplete:{ source:
'http://localhost:61361/BMatchMappings/GetUserByFilter' }" />

JavaScript

ko.bindingHandlers.autoComplete = {
    init: function (element, valueAccessor, allBindingsAccessor, viewModel, bindingContext) {
        var postUrl = allBindingsAccessor().source; // url to post to is read here
       // var selectedObservableArrayInViewModel = valueAccessor();

        $(element).autocomplete({
            minLength: 2,
            autoFocus: true,
            source: function (request, response) {
                 $.ajax({
                    url: postUrl,
                    data: { term: request.term },
                    dataType: "json",
                    type: "POST",
                    success: function (data) {
                        response(data);
                    }
                });
            },
            select: function (event, ui) {
                var selectedItem = ui.item;
//todo
           //     if (!_.any(selectedObservableArrayInViewModel(), function (item) { return item.id == selectedItem.id; })) { //ensure items with the same id cannot be added twice.
             //       selectedObservableArrayInViewModel.push(selectedItem);
               // }
            }
        });
    }
};