timezone - from Javascript to PHP

/*Javascript*/
    var d=new Date();
    var offset = d.getTimezoneOffset()*60;
    var timestamp = Math.ceil(d / 1000); //give this to PHP
    console.log('offset:'+offset);
    console.log('timestamp:'+timestamp);
    console.log(d.show());

/*PHP*/
    $offsetServer= date_offset_get(new DateTime); //in hour
    echo "Offset server : "; echo $offsetServer; echo "\n";

    $today = new DateTime("now");
    echo "Current date server : "; echo date('Y/m/d H:i:s', $today->getTimestamp()); echo "\n";

    $ts=1392381052;         //in minute - get by javascript
    $offsetClient=18000;    //in seconde - get by javascript
    $offset=$offsetClient+$offsetServer; //in second

    $modifiedServer=$today;
    $modifiedServer=$modifiedServer->setTimestamp($ts);
    echo "Modified date server : "; echo date('Y/m/d H:i:s', $modifiedServer->getTimestamp()); echo "\n";
    $modifiedClient=$today;
    $modifiedClient->setTimestamp($ts-$offset);
    echo "Modified date client : "; echo date('Y/m/d H:i:s', $modifiedClient->getTimestamp()); echo "\n";