Make sure you aren't iframed!

framebust.html

<!-- Crazy, but consistent method: -->
<style>
    body { display: none; }
</style>

<script>
if (self === top) {
   documents.getElementsByTagName("body")[0].style.display = 'block';
} else {
    top.location = self.location;
}
</script>

<!-- Inconsistent method: -->
<script>
if (top.location != location) {
  top.location = self.location;
}
</script>

server.js

X-Frame-Options: DENY                prevents framing code at all
X-Frame-Options: SAMEORIGIN          prevents framing by external sites
X-Frame-Options: ALLOW-FROM origin   allows framing only by the specified origin