Ajax In Firefox Plugin

Question

Is there any way to send Ajax requests to server from a Firefox plugin? If yes, how? If no, how do we have client server communication in Firefox plugins?

I want to get some JSON data from server and manipulate the DOM object according to the client input.

I am pretty a beginner in plugin programming.

Answer 1

You can send ajax requests from firefox extension using xmlHTTPRequest, like in any other web application.

Answer 2

From a contentscript you should add the permissions to access cross-domain content, URLs you want to:

"permissions": {
    "cross-domain-content": ["http://example.org/", "http://example.com/"]
}

More info in the documentation.

Answer 3

Here's a simple snippet that does XHR request, WITHOUT cookies (due to flag Ci.nsIRequest.LOAD_ANONYMOUS can remove to send with cookies) (MDN :: Info on flags]. Copy this first code block in, then see usage examples below.

var {Cu: utils, Cc: classes, Ci: instances} = Components;
Cu.import('resource://gre/modules/Services.jsm');
function xhrGetPost(url, post_data, cb) {
    let xhr = Cc["@mozilla.org/xmlextras/xmlhttprequest;1"].createInstance(Ci.nsIXMLHttpRequest);

    let handler = ev => {
        evf(m => xhr.removeEventListener(m, handler, !1));
        switch (ev.type) {
            case 'load':
                if (xhr.status == 200) {
                    cb(xhr.response);
                    break;
                }
            default:
                Services.prompt.alert(null, 'XHR Error', 'Error Fetching Package: ' + xhr.statusText + ' [' + ev.type + ':' + xhr.status + ']');
                break;
        }
    };

    let evf = f => ['load', 'error', 'abort'].forEach(f);
    evf(m => xhr.addEventListener(m, handler, false));

    xhr.mozBackgroundRequest = true;
    if (post_data == undefined) {
        post_data = null;
    }
    if (post_data) {
          xhr.open('POST', url, true);
    } else {
        xhr.open('GET', url, true);
    }
    xhr.channel.loadFlags |= Ci.nsIRequest.LOAD_ANONYMOUS | Ci.nsIRequest.LOAD_BYPASS_CACHE | Ci.nsIRequest.INHIBIT_PERSISTENT_CACHING;
    //xhr.responseType = "arraybuffer"; //dont set it, so it returns string, you dont want arraybuffer. you only want this if your url is to a zip file or some file you want to download and make a nsIArrayBufferInputStream out of it or something
    xhr.send(post_data);
}

Example usage of for POST:

var href = 'http://www.bing.com/'
xhrGetPost(href, 'post_data1=blah&post_data2=blah_blah', data => {
    Services.prompt.alert(null, 'XHR Success', data);
});

Example usage of for GET:

var href = 'http://www.bing.com/'
xhrGetPost(href, null, data => {
    Services.prompt.alert(null, 'XHR Success', data);
});