frameguard/README.md

Middleware to set X-Frame-Options headers

# X-Frame-Options middleware

The `X-Frame-Options` HTTP header restricts who can put your site in a frame which can help mitigate things like [clickjacking attacks](https://en.wikipedia.org/wiki/Clickjacking). The header has two modes: `DENY` and `SAMEORIGIN`.

This header is superseded by [the `frame-ancestors` Content Security Policy directive](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/frame-ancestors) but is still useful on old browsers.

If your app does not need to be framed (and most don't) you can use `DENY`. If your site can be in frames from the same origin, you can set it to `SAMEORIGIN`.

Usage:

```javascript
const frameguard = require("frameguard");

// Don't allow me to be in ANY frames:
app.use(frameguard({ action: "deny" }));

// Only let me be framed by people of the same origin:
app.use(frameguard({ action: "sameorigin" }));
app.use(frameguard()); // defaults to sameorigin
```

A legacy action, `ALLOW-FROM`, is not supported by this middleware. [Read more here.](https://github.com/helmetjs/helmet/wiki/How-to-use-X%E2%80%93Frame%E2%80%93Options's-%60ALLOW%E2%80%93FROM%60-directive)