JavaScript
<!DOCTYPE HTML>
<html lang="ja-JP">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
</body>
<script type="text/javascript">
var data1 = 128;
var data2 = -256;
var abs1 = Math.abs(data1);
var abs2 = Math.abs(data2);
var abs3 = Math.abs(data1) * -1;
var abs4 = Math.abs(data2) * -1;
var str = abs1 + "<br>" + abs2 + "<br>" + abs3 + "<br>" + abs4;
document.getElementsByTagName("body")[0].innerHTML = str;
</script>
</html>
PHP
<?php
header("Content-type: text/html; charset=utf-8");
$data1 = 128;
$data2 = -256;
echo abs($data1) . "<br>";
echo abs($data2) . "<br>";
echo abs($data1) * -1 . "<br>";
echo abs($data2) * -1 . "<br>";
?>