JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-2.2.2.js"></script>
<input type="text" id="caption" />

JavaScript

$(document).ready(function(){
    $('#caption').on('keypress', function () { 
        var n = $(this).val();
        if(n.indexOf("#") > -1){
            window.alert("There's a hash");
        }else{
             window.alert("There's not a 	hash");
        }

   });
});