HTTP request observer in restartless FF add-on

Question

I'm working on a restartless FF add-on that will change a header property in HTTP requests (specifically user agent) from a particular page.

I've been looking at the HTTP request observers documentation https://developer.mozilla.org/en-US/docs/Setting_HTTP_request_headers#Observers but this doesn't seem to be available in the restartless SDK. Am I missing something? Do I have another option for changing the user-agent of requests coming from a particular page?

Thanks!

Answer 1

copy paste, this will add a custom header when going to any google site:

const {Cu, Ci} = require('chrome'); //im not sure about this line plz verify, im not an sdk guy but know a bit about it
Cu.import('resource://gre/modules/Services.jsm');

var httpRequestObserver =
{
    observe: function(subject, topic, data)
    {
        var httpChannel, requestURL;

        if (topic == "http-on-modify-request") {
            httpChannel = subject.QueryInterface(Ci.nsIHttpChannel);
            requestURL = httpChannel.URI.spec;

            if (requestURL.indexOf('google.com') > -1) {
                httpChannel.setRequestHeader('MyCustomRequestHeader', 'hiiii', false);
            }

            return;
        }
    }
};

Services.obs.addObserver(httpRequestObserver, "http-on-modify-request", false);
//Services.obs.removeObserver(httpRequestObserver, "http-on-modify-request", false); //run this on shudown of your addon otherwise the observer stags registerd

also a note. because you want to change user request make sure that third parameter is set to false in httpChannel.setRequestHeader('MyCustomRequestHeader', 'hiiii', false); otherwise it will merge the pre-existing user agent with the new one you supply