无法访问$ getJSON之外的变量

Question

我正尝试从API获取数据并将其存储在地图标记中。我确实将调试器发现正在获取数据并将其存储在$ .getJSON内的变量，并且当我尝试在其外部访问它时返回的未定义<。 / p>

这是代码的一部分

var Location = function(data) {
  var self = this;
  this.name = data.name;
  this.lat = data.lat;
  this.long = data.long;
  this.street ;
  this.city ;

  this.visible = ko.observable(true);

  var foursquareURL = 'https://api.foursquare.com/v2/venues/search?ll='+ this.lat + ',' + this.long + '&client_id=' + clientID + '&client_secret=' + clientSecret + '&v=20180909' + '&query=' + this.name;

  $.getJSON(foursquareURL).done (function(data) {
    var results = data.response.venues[0];
    this.street = results.location.formattedAddress[0];
      this.city = results.location.formattedAddress[1];
    }).fail(function() {
    alert("There was an error with the Foursquare API call. Please refresh the page and try again to load Foursquare data.");
  });

  this.contentString = '<div class="info-window-content"><div class="title"><b>' + data.name + "</b></div>" +
        '<div class="content">' + this.street + "</div>" +
        '<div class="content">' + this.city + "</div>";

    addMarkerToGroup(group, {lat:data.lat, lng:data.long},self.contentString);
  // addInfoBubble(map);
};

function addMarkerToGroup(group, coordinate, html) {
  var marker = new H.map.Marker(coordinate);
  // add custom data to the marker
  marker.setData(html);
  group.addObject(marker);
}

我需要的是this.street和this.city。，但是它会不断获取每个查询的数据，然后返回未定义的数据。