Jquery ajax – Ajax calls DURING another Ajax call to receive server's task calculation status and display it to the client as a progression bar

I’m trying to figure out if there’s any chance to receive the status of completion of a task (triggered via an ajax call), via multiple (time intervalled) ajax calls.
Basically, during the execution of something that could take long, I want to populate some variable and return it’s value when asked.

Server code looks like this:

function setTask($total,$current){
    $this->task['total'] = $total;
    $this->task['current'] = $current;
}

function setEmptyTask(){
    $this->task = [];
}

function getTaskPercentage(){
    return ($this->task['current'] * 100) / $this->task['total'];
}

function actionGetTask(){
    if (Yii::$app->request->isAjax) {

        Yii::$app->response->format = yiiwebResponse::FORMAT_JSON;

        return [
            'percentage' => $this->getTaskPercentage(),
        ];
    }
}

Let’s say I’m in a for loop, and I know how many times I iterate over:

function actionExportAll(){
    $size = sizeof($array);
    $c = 0;
    foreach($array as $a){
        // do something that takes relatively long
        $this->setTask($size,$c++);
    }
}

While in the client side i have this:

function exportAll(){
    var intervalId = setInterval(function(){
        $.ajax({
            url: '/get-task',
            type: 'post',
            success: function(data){
                console.log(data);
            }
        });
    },3000);

    $.ajax({
        url: '/export-all',
        type: 'post',
        success: function(data){
            clearInterval(intervalId); // cancel setInterval
            // ..
        }
    });
}

This looks like it could work, besides the fact that ajax calls done in the setInterval function are completed after “export-all” is done and goes in the success callback.
There’s surely something that I’m missing in this logic.
Thanks