JSFiddle - React, Tailwind, and code Playground

HTML

<p>
  <input type=button id=up value="jump up" />
</p>
<p>
  <input type=button id=down value="jump down" />
</p>

JavaScript

if(localStorage.getItem("uKtcY-cv") !== null){
  $("<p>").text("welcome back!").appendTo(document.body)
}else{
  $("<p>").text("welcome for the first time!").appendTo(document.body)
}

function jump(howHigh){
    var currentVal = (+localStorage.getItem("uKtcY-cv"))||0;
    prevVal = currentVal; 
    currentVal = currentVal + howHigh; 
    localStorage.setItem("uKtcY-cv", currentVal);
    $("<p>").text(currentVal).appendTo(document.body)
}

$("#up").click(function(){jump(1)})
$("#down").click(function(){jump(-1)})