Question

这是我正在制作的应用程序的代码。基本上，它会在地图上显示用户的所有位置以及他们用于登录标记的电话号码。由于某种原因，出现了一个错误，提示无法读取未定义的属性“ 0”。这是它所指的代码行。我的坐标显示在实时数据库中，所以我不知道为什么会引发此错误。我还提供了控制台的屏幕截图，告诉了错误。

picture of error

  lat: data.User.l[0],

<!DOCTYPE html>
<html>
  <head>
    <title>Geolocation</title>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <style>
      /* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
      #map {
        height: 100%;
      }
      /* Optional: Makes the sample page fill the window. */
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
    </style>
    <!-- Place this inside the HTML head; don't use async defer for now -->

    
<script src="https://www.gstatic.com/firebasejs/4.12.1/firebase.js"></script>
<script src="https://cdn.firebase.com/libs/geofire/4.1.2/geofire.min.js"></script>

  <script>
        
        var config = {
    apiKey: "",
    authDomain: "carrier-35d7c.firebaseapp.com",
    databaseURL: "https://carrier-35d7c.firebaseio.com",
    projectId: "carrier-35d7c",
    storageBucket: "carrier-35d7c.appspot.com",
    messagingSenderId: "827792028763"
  };
        if (!firebase.apps.length) {
            firebase.initializeApp(config);
        }
        
        //Create a node at firebase location to add locations as child keys
        //var locationsRef = firebase.database().ref("locations");
        
        // Create a new GeoFire key under users Firebase location
        //var geoFire = new GeoFire(locationsRef.push());
        //Create a node at firebase location to add locations as child keys
        //confirm(firebase.auth().currentUser)
    
    //var a = localStorage.getItem('phoneNumber');
    
 
        var locationsRef = firebase.database().ref("locations");
        var pushRef = locationsRef.push()
        var postID = pushRef.key;
      console.log(postID);
      
      // Create a new GeoFire key under users Firebase location
      // replace var geoFire = new GeoFire(locationsRef.push()); with
      var geoFire = new GeoFire(pushRef); 
      </script>


  </head>
  <body>
    <div id="map"></div>
    <script>
      
    
      // Note: This example requires that you consent to location sharing when
      // prompted by your browser. If you see the error "The Geolocation service
      // failed.", it means you probably did not give permission for the browser to
      // locate you.
      var map, infoWindow;
      var lat, lng;
      function initMap() {
        map = new google.maps.Map(document.getElementById('map'), {
          center: {lat: -34.397, lng: 150.644},
          zoom: 18
          //mapTypeId: google.maps.MapTypeId.ROADMAP
        });
        infoWindow = new google.maps.InfoWindow;
        // Try HTML5 geolocation.
        if (navigator.geolocation) {
          navigator.geolocation.getCurrentPosition(function(position) {
            lat = position.coords.latitude;
            lng = position.coords.longitude;
            
            var pos = {lat: lat, lng: lng, name };
                _setGeoFire();
              var locationsRef = firebase.database().ref("locations");
locationsRef.on('child_added', function(snapshot) {
  var data = snapshot.val();
 
   
   
  
  var marker = new google.maps.Marker({
    position: {
      lat: data.User.l[0],
      lng: data.User.l[1]
     
    },
    map: map,
     
      
   // new google.maps.Size(42, 68)
  });
 a = localStorage.getItem('phone')
  
  var database = firebase.database();
              var fruitsRef = database.ref('locations/'+ postID + '/User/g');
              fruitsRef.update ({
                number: (a)
              })
            
  
  marker.addListener('click', (function(data) {
    return function(e) {
      infoWindow.setContent(this.getPosition().toUrlValue(6) + "<br>" + data.User.g.number);
      infoWindow.open(map, this);
    }
  }(data)));
  
});
          
            infoWindow.setPosition(pos);
            infoWindow.setContent('Current Location');
            infoWindow.open(map);
            map.setCenter(pos);
          }, function() {
            handleLocationError(true, infoWindow, map.getCenter());
          });
        } else {
          // Browser doesn't support Geolocation
          handleLocationError(false, infoWindow, map.getCenter());
        }
      }
      function handleLocationError(browserHasGeolocation, infoWindow, pos) {
        infoWindow.setPosition(pos);
        infoWindow.setContent(browserHasGeolocation ?
                              'Error: The Geolocation service failed.' :
                              'Error: Your browser doesn\'t support geolocation.');
        infoWindow.open(map);
      }
     function _setGeoFire(){
geoFire.set("User", [lat, lng] ).then(()=>{
  console.log("Location added");
  
  pushRef.child("User").onDisconnect().remove();
}).catch(function(error) {
  console.log(error);
});
}
    </script>
    <script 
    src="https://maps.googleapis.com/maps/api/js?key=AIzaSyD2nPlSt_nM7PSKD8So8anbUbBYICFWcCA&callback=initMap">
    </script>
  </body>
</html>

Firebase实时数据库返回错误“无法读取未定义的属性'0'”

0 个答案: