How to listen for Request complete event? Or how to get response object back

Question

I am totally new to firefox extensions and javascript. I have something like this:

var json = JSON.parse(links);
for (var i = 0; i < json.length; i++) {
    var link = json[i];
    Request({
        url: link.url,
        onComplete: function (response) {
            console.log(response.status);
        }
    }).get();
}

Now I need to do something based on a status of a response object. But I would like to continue in my for loop because I need that link object...

On documentation page of Request https://developer.mozilla.org/en-US/Add-ons/SDK/High-Level_APIs/request is mentioned 'complete' event which is emitted after response being returned but I really don't know how to listen for events like this.

I really don't know how to approach this but this is result I need:

var json = JSON.parse(links);
for (var i = 0; i < json.length; i++) {
    var link = json[i];
    Request({
        url: link.url,
        onComplete: function (response) {
            // something
        }
    }).get();
    // I need RESPONSE object here
    if(response.status == 404) {
         // do something with link object
    }
}

Answer 1

onComplete is invoked asynchronously. For cases like these you need to 'save' the reference to a link object in a closure.

var fetchAndProcess = function(link) {
    Request({
        url: link.url,
        onComplete: function(response) {
            if (response.status == 404) {
                console.log(link); // 'saved' in fetchAndProcess
                // do something with link object
            }
        }
    }).get();
};

var json = JSON.parse(links);
for (var link of json) {
    fetchAndProcess(link);
}