Google maps JavaScript Marker Not Working in httpRequest

i have written the following code and google markers are not working. If I put the marker creation outside the httpRequest work fine. What is the problem ?

var xhttp = new XMLHttpRequest();
                xhttp.onreadystatechange = function () {
                    if (this.readyState == 4 && this.status == 200) {
                        var coordinates = JSON.parse(this.responseText);
                        for (point of coordinates) {
                            console.log(point);
                            var marker = new google.maps.Marker({
                                map: map,
                                position: new google.maps.LatLng(point[0], point[1])
                            })
                        }
                    }
                };
                xhttp.open("GET", "../php/createAdresses.php", false);
                xhttp.send();