So, starting from the beginning we will need few libraries for using Jquery Autocomplete . Basically, that is included in Jquery UI js. So we need to add these scripts in our webpage

<link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>

So, after adding these scripts in the head section of your webpage. We have to add this code in our webpage

 <script>
        

        $(document).ready(function () {

            var datalist = ["hindi", "english", "math", "science", "geography", "socialscience", "sanskrit"]
            $("#TestAutocomplete").autocomplete({
                source: datalist,

                response: function (event, ui) {
                    ui.content.push({
                        value: '', label: "Add new item"
                    });
                    ui.content.push({
                        value: event.target.value, label: event.target.value
                    });
                },


            }).data("ui-autocomplete")._renderItem = function (ul, item) {
                if (item.value == '') {
                    return $('<li class="ui-state-disabled" style="padding-left:5px;">' + item.label + '</li>').appendTo(ul);
                }
                var expression = new RegExp(this.term, 'gi');
                var highlight = item.label.replace(expression, "<span style='font-weight:bold;'>" + this.term + "</span>")
                return $("<li>")
                    .append("<a>" + highlight + "</a>")
                    .appendTo(ul);


            }
        })



    </script>

So, this function will be placed in document ready which will initialize the autocomplete. You will notice that we have create a array variable there. Which contains all the items of the Autocomplete.

.data("ui-autocomplete")._renderItem = function (ul, item) {
                if (item.value == '') {
                    return $('<li class="ui-state-disabled" style="padding-left:5px;">' + item.label + '</li>').appendTo(ul);
                }
                var expression = new RegExp(this.term, 'gi');
                var highlight = item.label.replace(expression, "<span style='font-weight:bold;'>" + this.term + "</span>")
                return $("<li>")
                    .append("<a>" + highlight + "</a>")
                    .appendTo(ul);


            }

This method is fired whenever Jquery Autocomplete tries to create html for rendering. Here we have adding bold wherever searche text is found.

@{
    ViewData["Title"] = "Autocomplete";
}
<style>

    .ui-state-active,
    .ui-widget-content .ui-state-active,
    .ui-widget-header .ui-state-active,
    a.ui-button:active,
    .ui-button:active,
    .ui-button.ui-state-active:hover {
        background: transparent !important;
        font-weight: normal;
        color: black !important;
        width: 100% !important;
        min-width: 200px !important;
        border:0px!important;
    }
</style>

<link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>


<div style="margin-top:50px;">
    <label for="TestAutocomplete">Subjects</label>
    <input type="text" id="TestAutocomplete" class="validate" />


</div>
@section scripts{
    <script>
        

        $(document).ready(function () {

            var datalist = ["hindi", "english", "math", "science", "geography", "socialscience", "sanskrit"]
            $("#TestAutocomplete").autocomplete({
                source: datalist,

                response: function (event, ui) {
                    ui.content.push({
                        value: '', label: "Add new item"
                    });
                    ui.content.push({
                        value: event.target.value, label: event.target.value
                    });
                },


            }).data("ui-autocomplete")._renderItem = function (ul, item) {
                if (item.value == '') {
                    return $('<li class="ui-state-disabled" style="padding-left:5px;">' + item.label + '</li>').appendTo(ul);
                }
                var expression = new RegExp(this.term, 'gi');
                var highlight = item.label.replace(expression, "<span style='font-weight:bold;'>" + this.term + "</span>")
                return $("<li>")
                    .append("<a>" + highlight + "</a>")
                    .appendTo(ul);


            }
        })



    </script>
}

So , this is the complete code available for Jquery Autocomplete. You can also download the source code by downloading from the attachment button. Or you can have a look at our youtube video for more details.