addon-proxy

Provides a clean API for Firefox addon-sdk extensions to modify incoming HTTP responses. To begin modifying responses, just call rewrite({...}) and pass an object with the optional properties html, js, other.

In addition, the argument can have a responses property, which is a shorthand to return pre-computed responses if the requested URL contains the provided pattern (but note that the original request is still sent, and the response maintains the original response's status code and headers).

Usage

var proxy = require("addon-proxy");

proxy.rewrite({
  html: function(data, req) {
    return foo(data);
  },
  js: function(data, req) {
    // req is the nsIHttpChannel that is passed to nsIStreamListener's methods.
    if (req.URI.host === "localhost")
      return data;
    else
      return bar(data);
  },
  other: function(data, req) {
    // or don't pass it at all, default behavior is just `return data;`
    return data;
  },
  responses: {
    "fakefile.js": "alert(fake)",
    "mydir/myfile": file.read(path)
  }
});

You can temporarily disable html and js transformations for a particular response by appending proxypass=true to the URL querystring.

To keep the API simple, this is a caching proxy, i.e. it does not stream responses, it only forwards data when the request has been fully downloaded from the server.