Question

我在Angular控制器中有以下代码......

function doWork() {
  // show the loading modal
  $scope.modal = $ionicLoading.show({
    content: 'Fetching current location...',
    showBackdrop: false
  });

  console.log("get orig pos");

  // get the position
  PositionService.getPosition(posOptions)
    .then(function(positionArr) {
      // got 1st location // this doesn't execute!
      console.log("got original pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
      $scope.modal.hide();
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
      $timeout(function() {
        $scope.modal.hide();
      }, 3000);          
    });

    console.log("get next pos");

  PositionService.getPosition(posOptions)
    .then(function(positionArr) {
      // got 2nd location // this does execute!
      console.log("got new pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
    });
 }

当我运行程序时，PositionService.getPosition函数被调用两次，正如我所期望的那样，但只执行了一个then部分。不应该执行两个then块，还是我误解了Javascript中的工作方式？这是getPosition函数的内容......

   getPosition : function(posOptions) {
      return $cordovaGeolocation
        .getCurrentPosition(posOptions)
        .then(function(position) {
          positionArr = positionArr.concat({
            position: position,
            status: 'new'
          });
          return positionArr;
        }, function(err) {
          console.log("PositionService: error getting position");
          return err;
        });
    },

编辑：

这是控制台输出的请求...

Answer 1

您应该链接您对位置服务的调用：

var p1 =  PositionService.getPosition(posOptions)
    .then(function(positionArr) {
      // got 1st location
      console.log("got original pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
      $scope.modal.hide();
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
      $timeout(function() {
        $scope.modal.hide();
      }, 3000);          
    });

var p2 = p1.then (function() {
     return PositionService.getPosition(posOptions);
   }).then(function(positionArr) {
      // got 2nd location
      console.log("got new pos: " + positionArr.length);          
      $scope.locationArray = positionArr;
      $scope.dataReceived = true;
    }, function(err) {
      // something went wrong
      console.log("something wrong in getPos");
    });

Answer 2

首先.then（）回调是一次成功＆＃39;另一个是错误＆＃39;。所以它是这两者中的一个。防爆。 http请求可以是＆＃39; 200＆＃39;或者＆＃39; 404＆＃39; （或其他错误）。

请参阅：http://blog.mediumequalsmessage.com/promise-deferred-objects-in-javascript-pt1-theory-and-semantics

关于Javascript的困惑＆＃39;然后＆＃39;行为

2 个答案: