<!DOCTYPE html>
<html>
<head>
<style>
#myBtn {
position: absolute;
}
</style>
</head>
<body>
<button type="button" id="myBtn" onclick="myFunction()">Set bottom position to 100 px</button>
<script>
function myFunction() {
document.getElementById("myBtn").style.bottom = "100px";
}
</script>
</body>
</html>