solved.html

<html>
<head>
<title>Maju mundur Cantik</title>
</head>
<body>
<button id="btn" onclick="getName(this);" name="button1">Maju</button>
<button id="btn" onclick="getName(this);" name="button2">Mundur</button>
<script>
function getName(content){
var btn = content.getAttribute('name');
    alert('Your Clicked button is "' + btn + '"');
}
</script>
</body>
</html>