JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <form>
        <input type="number" id="quantidade" name="quantidade" value="" min="1" size="8" autocomplete="off" /> 
        <input type="text" id="teste" name="teste" value=""/>
    </form>
    <button type="button" class="ve">Verificar</button>    
</div>

JavaScript

$(".ve").on("click", function(){ alert('res');
   $(this).parent().find('form')[0].reset();
});

$(".ha").on("click", function(){
   $("#quantidade").removeAttr("disabled");
});

$("#quantidade").on("change",function(){
    $("#teste").val(parseInt($("#quantidade").val()) *2);
});