JSFiddle - React, Tailwind, and code Playground

HTML

<div style="width:100%" align="center">

    <form id="frmRegister" role="form" target="_self">

      <div class="form-group" align="center">
        <span>Registration</span>
      </div>

      <div class="form-group">
        <input id="txtRegUsername" name="txtRegUsername" type="text" class="form-control" maxlength="20" placeholder="USERNAME" autocomplete="on">
      </div>

      <div class="form-group">
        <input id="txtRegEmail" name="txtRegEmail" type="text" class="form-control" maxlength="255" placeholder="EMAIL" autocomplete="on">
      </div>

      <div class="form-group">
        <input id="txtRegPassword" name="txtRegPassword" type="password" class="form-control" maxlength="100" placeholder="PASSWORD">
      </div>

      <div class="form-group">
        <input id="txtRegConfirmPassword" name="txtRegConfirmPassword" type="password" class="form-control" maxlength="100" placeholder="CONFIRM PASSWORD">
      </div>

      <div class="form-group">

        <button id="butRegister" type="button" class="btn btn-default">
          Register
        </button>

      </div>  

    </form> 

  </div>

JavaScript

$(document).ready(function() {
      
      $('#txtRegUsername').on("blur", function(e) { 
        //if ($('#txtRegUsername').val()!=="") {
          alert("username Blur event");
        //}
      });

      //$('#txtRegUsername').on("focus",function(e) { 
      //alert("username Focus event");
      //});
     
      $('#txtRegEmail').on("blur", function(e) {
        //if ($('#txtRegEmail').val()!=="") {
        alert("email Blur event");
        //}
      });

      //$('#txtRegEmail').on("focus",function(e) { 
      //alert("email Focus event");
      //});
           
      $('#txtRegPassword').on("blur", function(e) { 
        //if ($('#txtRegPassword').val()!=="") {
          alert("password Blur event");
        //}
      });

      //$('#txtRegPassword').on("focus",function(e) { 
      //alert("password Focus event");
      //});

      $('#txtRegConfirmPassword').on("blur", function(e) { 
        //if ($('#txtRegConfirmPassword').val()!=="") {
          alert("confirm_password Blur event");
        //}
      });

      //$('#txtRegConfirmPassword').on("focus",function(e) { 
      //alert("confirmpassword Focus event");
      //});

    });