JSFiddle - React, Tailwind, and code Playground

HTML

<input myVar="5" />
<button value="go" />

JavaScript

$("button").click(function() 
{
    var attrVal = $("input").attr("myVar");    
    var addOne = attrVal + 1;
    var substractOne = attrVal - 1;
    
    alert("+1 -> " + addOne + ", -1 -> " + substractOne);
});