JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>

<input type="checkbox" id="mycheckbox">
<br>    
<input type="button" value="Click" id="btn">

JavaScript

$(document).ready(function(){
    $('#btn').click(function(){
        
        if($( '#mycheckbox' ).prop( "checked" ) == true){
               alert('desmarcado')
               $( '#mycheckbox' ).prop( "checked" , false)
        } else {
             alert('marcado')
             $( '#mycheckbox' ).prop( "checked" , true)
        }
    })
    
})