<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<button id="at">arttır</button>
<button id="az">alat</button>
<h1 id="deger"></h1>
<hr>
<h1 style="color: red;" id="deger2"></h1>
<script>
let at = document.getElementById("at")
let az = document.getElementById("az")
let deger = document.getElementById("deger")
let deger2 = document.getElementById("deger2");
let value = 0
at.addEventListener("click",function(e){
value++
deger.innerHTML = value.
deger2.innerHTML = value.
e.preventDefault();
})
az.addEventListener("click",function(e){
value--
deger.innerHTML = value.
deger2.innerHTML = value.
e.preventDefault();
})
</script>
</body>
</html>