Q:

AngularJS - how can I send data to the php page with $http.post? 

I can't understand why the data object seems doesn't exist at php server side page. 
Angular
$http.post("serverside.php", {"data1":"okpass"}).success(function(data, status, header, config){
                console.log(data);// 
                console.log(status);//202 
                console.log(header);//function (c){a||(a=nc(b));return c?a[O(c)]||null:a}
    });

PHP
if( isset($_POST["data1"]) && $_POST["data1"] == "okpass" ){
    echo "It works!"; 
    exit(0);
}

A:

Angulars http.post does not send form data, so you cant rely on phps $_POST.  It sends json data.  You can get the data like so:
$request = json_decode(file_get_contents("php://input"), true);
if( isset($request["data1"]) && $request["data1"] == "okpass" ){
    echo "It works!"; 
    exit(0);
}

