JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://code.jquery.com/ui/1.11.4/jquery-ui.min.js"></script>
<link rel="stylesheet" href="http://code.jquery.com/ui/1.11.4/themes/black-tie/jquery-ui.css">
<input id="txt" type="text" />

JavaScript

var tags = ["ActionScript", "AppleScript", "Asp", "BASIC", "C", "C++", "Clojure", "COBOL", "ColdFusion", "Erlang", "Fortran", "Groovy", "Haskell", "Java", "JavaScript", "Lisp", "Perl", "PHP", "Python", "Ruby", "Scala", "Scheme"];
var usuarios = ["João", "Pedro", "Maria", "Juca", "John", "Jane", "Augusto", "Lucas"];

$(document).ready(function () {
    $("#txt").autocomplete({
        source: function (req, responseFn) {
            var source = [];
            if (req.term.startsWith("@")) 
                source = usuarios;
            else if (req.term.startsWith("#"))
                source = tags;
                    
            var encontrados = $.grep(source, function (item, index) {                
                return item.toLowerCase().startsWith(req.term.substring(1).toLowerCase());
            });
            responseFn(encontrados);
        }
    });

});