JS 2

var canSaveCookie = (function () {

$.cookie("testSaveCookie", {});

var ok = $.cookie("testSaveCookie") !== null;

$.removeCookie("testSaveCookie");

return ok;

})();

function addTaskList(project_management_id, date) {
$.ajax({
url: "<?= Yii::$app->request->baseUrl ?>/task-detail/ajax-list-task",
dataType: 'json',
data: {'project_management_id' :project_management_id, 'ask_date': date},
type: 'POST',
success: function (res) {
tasks = JSON.parse(res.items);

// defaultEventClick(tasks[0]);
console.log(tasks.length);
// avoid duplicate append task list
clearPopupTaskList();

$.each(tasks, function(id, value) {
    $('#popup_task_id')
       .append($("<option></option>")
       .attr("value", value['id'])
       .text(value['task_name']));
});

defaultEventClick(tasks[0]);
handleFileUpload(tasks[0]['id']);
// $('#popup_task_id')
// .append($("<option></option>"))
// .attr("value", '')
// .text('New task');

// fill data

}
});
}

function clearPopupTaskList() {
$('#popup_task_id')
    .find('option')
   .remove()
   .end()
}

Object Find key by value:
Object.prototype.getKeyByValue = function( value ) {
   for( var prop in this ) {
       if( this.hasOwnProperty( prop ) ) {
            if( this[ prop ] === value )
                return prop;
       }
   }
}