Untitled

<!DOCTYPE HTML>
<html>
<head>
    <meta charset="utf-8">
    <title>removeEventListener</title>
</head>
<body>
<input id="elem" value="old">
<button class="button">Клацни на меня</button>

<script>
    let elem = document.querySelector('#elem'); elem.value = 'new';
    let value = elem.getAttribute('value');
    console.log(value);

</script>
</body>
</html>