JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" name="checkbox"><br/>
<input type="text" name="qtybox">

CSS

#cloneArea
{
 width:90%; height:100px; background-color:#EFEFEF;   
}

JavaScript

$(function(){

    $('input[name="checkbox"]').click(function(){
        $('input[name="qtybox"]').val(0);
        if($(this).is(':checked'))
        {
            $('input[name="qtybox"]').val(1);
        }
       
    });
    
});