Javascript 如何从异步php数据库搜索向地理编码器发送地址_Javascript_Php_Ajax_Google Maps Api 3_Google Geocoding Api

Javascript 如何从异步php数据库搜索向地理编码器发送地址

javascript php ajax google-maps-api-3

Javascript 如何从异步php数据库搜索向地理编码器发送地址,javascript,php,ajax,google-maps-api-3,google-geocoding-api,Javascript,Php,Ajax,Google Maps Api 3,Google Geocoding Api,我正试图让我的谷歌地图应用程序等待来自使用php的数据库调用的ajax调用的响应。我知道我需要使用回调，但我不确定在这种情况下如何实现它们，因为geocoder api也是异步的我尝试了来自和的答案，但我不确定如何编辑它来处理我的案例 db.php $mysqli = new mysqli("host", "user", "pass", "db"); (perform query)... echo json_encode($result_assoc_array); location.php

我正试图让我的谷歌地图应用程序等待来自使用php的数据库调用的ajax调用的响应。我知道我需要使用回调，但我不确定在这种情况下如何实现它们，因为geocoder api也是异步的

我尝试了来自和的答案，但我不确定如何编辑它来处理我的案例

db.php

$mysqli = new mysqli("host", "user", "pass", "db");
(perform query)...
echo json_encode($result_assoc_array);

location.php

<html>
(html boilerplate)...
<body>
<div id="map"></div>
<script>
var map;
var homeAddress;

var oReq = new XMLHttpRequest();
oReq.onload = function() {
    homeAddress = JSON.parse(this.responseText).address; //main field I want is address
};
oReq.open("get", "db.php", true);

oReq.send();

function initMap() {
    map = new google.maps.Map(document.getElementById('map'), {
        center: { lat: -34.397, lng: 150.644 },
        zoom: 15,
    });

    var bounds = new google.maps.LatLngBounds();
    var geocoder = new google.maps.Geocoder();
    var markers = [];

    geocoder.geocode({
        'address': JSON.stringify(homeAddress)
    }, function(results, status) {
        if (status == google.maps.GeocoderStatus.OK) {
            console.log(results);
            map.setCenter(results[0].geometry.location);
            var marker = new google.maps.Marker({
                map: map,
                position: results[0].geometry.location
            });
            bounds.extend(marker.position);
            markers.push(marker);
        } else {
            alert("Geocode was not successful for the following reason: " + status);
        }
    });
 (more logic)
</script>
<script src="https://maps.googleapis.com/maps/api/js?key=myKey&callback=initMap&libraries=geometry" async defer></script>
</body>
</html>

这应该会给我一个以db地址为中心的映射，但我得到的地理编码没有成功，原因如下：由于homeAddress未定义，因此请求无效。

将ajax请求放在initMap中，当地址可用时，在其回调函数中调用地理编码程序：

function initMap() {
    map = new google.maps.Map(document.getElementById('map'), {
        center: { lat: -34.397, lng: 150.644 },
        zoom: 15,
    });

    var bounds = new google.maps.LatLngBounds();
    var geocoder = new google.maps.Geocoder();
    var markers = [];

    var oReq = new XMLHttpRequest();
    oReq.onload = function() {
      homeAddress = JSON.parse(this.responseText).address; //main field I want is address
      geocoder.geocode({
        'address': JSON.stringify(homeAddress)
      }, function(results, status) {
        if (status == google.maps.GeocoderStatus.OK) {
          console.log(results);
          map.setCenter(results[0].geometry.location);
          var marker = new google.maps.Marker({
            map: map,
            position: results[0].geometry.location
          });
          bounds.extend(marker.position);
          markers.push(marker);
        } else {
          alert("Geocode was not successful for the following reason: " + status);
        }
      });
    };
    oReq.open("get", "db.php", true);

    oReq.send();    
 (more logic)