return

js/script.js

function funMake(arg0, arg1) {
return arg0 + arg1;
}

function funMake(arg0, arg1) {
 return arg0 + arg1;
}

index.html

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script src="js/script.js"></script>
</head>
<body>
<script>
document.write(funMake(10, 20));
</script>
</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>New Page</title>
<script src="js/script.js"></script>
</head>
<body>
<script>
document.write(funMake(10, 20));
</script>
</body>
</html>