JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <head>
    </head>
    <body>
        
<div id="incdec">
    <input type="text" value="0" />
    <button id="up" >++</button>
    <button id="down" >- -</button>
</div>
</body>
</html>

JavaScript

$(document).ready(function(){
    $("#up").on('click',function(){
        $("#incdec input").val(parseInt($("#incdec input").val())+1);
    });

    $("#down").on('click',function(){
        var value = (parseInt($("#incdec input").val())-1);
        var val = (value-1) < 0 ? 0 :value -1;
        $("#incdec input").val(val);
    });

});