a way to know when Angular $http is “requesting”

Question

I make an $http request when a user clicks a <button> and I disable/hide/show several elements on screen until the request comes back with either success or error

Is there a way to know that $http hasn't had a response yet? The way I am doing it right now is I have a var in my controller called $scope.requesting which I then use in my HTML page like so:

<img src="img/loader.gif" ng-show="requesting" />

so basically when $scope.requesting is true, show the spinning ajaxyish loader.

I'd like to ditch the $scope.requesting if possible and use whatever $http has to offer, if any at all.

Login Controller

function LoginForm($scope, $http)
{
    $scope.requesting = false;

    $scope.login = function()
    {
        $scope.requesting = true;

        $http.post('resources/request.php', data, {timeout:20000})
            .success(function(data, status, headers, config)
            {
                $scope.requesting = false;
            })
            .error(function(data, status, headers, config)
            {
                $scope.requesting = false;
            }
        );
    }
}

Answer 1

You can make use of $http.pendingRequests array of config objects for currently pending requests. It is possible to use it that way:

$scope.isLoading = function () {
   return $http.pendingRequests.length !== 0;
};

Answer 2

Try this directive: https://github.com/afeiship/angular-isloading

css:

body {
  font-family: 'STHeiti', 'Microsoft YaHei', Helvetica, Arial, sans-serif;
  -webkit-tap-highlight-color: rgba(0, 0, 0, 0)
}

.loading-widget {
  width: 100px;
  height: 100px;
  margin: auto;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  position: absolute;
}

.loading-widget,
.loading-widget[data-visible] {
  display: none;
}

.loading-widget[data-visible=true] {
  display: block;
}

.loading-widget img {
  width: 100%;
  height: 100%;
}

html:

<div class="loading-widget"
     isloading
     loading="loading"
     data-visible="{{loading}}"
>
  <img src="svg/default.svg" alt="">
</div>

javascript:

  angular.module('TestApp', ['nx.widget']);

  angular.module('TestApp').
  controller('MainCtrl', function ($http, $q, $rootScope) {
    $rootScope.loading = false;
    var s1 = $http.get('http://www.baidu.com');
    var s2 = $http.get('http://www.sina.com');
    var s3 = $http.get('http://www.163.com');
    var s4 = $http.get('http://www.qq.com');
    var s5 = $http.get('http://www.hao123.com');

    //you need a VPN if you're a Chinese(Thanks to the GFW)
    var s6 = $http.get('https://www.google.com/');


    $q.all([s1, s2, s3, s4, s5, s6]).then(function (responses) {
      console.log(responses);
    })


  });

 description:

• isloading <!--1.attach the directive-->
• loading="loading" <!--2.write the scope.loading to the app.$rootScope-->
• data-visible="{{loading}}" <!--2.read loading props for CSS-->

Answer 3

this jsbin project takes @DmitryEvseev's answer to the next step. It provides finer control over which requests can be used to trigger "loading...".

Those requests with { showLoader: true } are used to show the 'loading...' panel.

HTML

  <div ng-app="app">
    <div ng-controller="spinnerController as vm">
      <div ng-if="vm.isLoading()">Loading ...</div>
    </div>
  </div>

Javascript

angular
  .module('app', [])
  .config(config)
  .factory('httpLoader', httpLoader)
  .factory('httpLoaderInterceptor', httpLoaderInterceptor)
  .controller('spinnerController', spinnerController);

function config($httpProvider) {
  //adding the default http status code handler
  $httpProvider.interceptors.push('httpLoaderInterceptor');
}

function httpLoader() {
  var pendingReqs = {};
  var factory = {
    addPendingReq: addPendingReq,
    subtractPendingReq: subtractPendingReq,
    getPendingReqs: getPendingReqs
  };
  return factory;

  function addPendingReq(url) {
    console.log('adding url', url);
    pendingReqs[url] = true;
  }

  function subtractPendingReq(url) {

    console.log('removing url', url);
    delete pendingReqs[url];
  }

  function getPendingReqs() {
    return sizeOf(pendingReqs);
  }
}

function httpLoaderInterceptor($q, httpLoader) {

  var factory = {
    request: request,
    response: response,
    responseError: responseError
  };

  return factory;

  function request(config) {
    console.log('request', config.url);
    if (config.showLoader) {
      httpLoader.addPendingReq(config.url);
    }
    return config;
  }

  function response(res) {
    console.log('response', res.config.url);
    if (res.config.showLoader) {
      httpLoader.subtractPendingReq(res.config.url);
    }
  }

  function responseError(res) {
    console.log('responseError', res.config.url);
    if (res.config.showLoader) {
      httpLoader.subtractPendingReq(res.config.url);
    }
    return $q.reject(res);
  }
}

function spinnerController($http, httpLoader) {
  var self = this;
  self.isLoading = function() {
    return httpLoader.getPendingReqs() > 0;
  };

  $http.get('http://stackoverflow.com/posts/34561385',{
    showLoader: true
  });
  $http.get('http://www.amazon.com', {
    showLoader: true
  });
  $http.get('http://www.yahoo.com',{
    showLoader: true
  });
  $http.get('http://www.stackoverflow.com',{
    showLoader: true
  });
}

function sizeOf(obj) {
  var size = 0,
    key;
  for (key in obj) {
    if (obj.hasOwnProperty(key)) {
      size++;
    }
  }
  return size;
}

Answer 4

None of the answers here really nailed it for me, and I shun using $http.pendingRequests, so here's what I've done

My use case was that I had to show a simple "Loading.." message on the top of my viewport if I had any in-flight requests doing things on the server.

Inside .config, I've registered a new Interceptor. and inside there I've added a simple counter that increments by 1 per request and decrements per response.

$httpProvider.interceptors.push([function () {
    var pendingRequestsCounter = 0;
    return {
        request: function (request) {
            pendingRequestsCounter++;
            if (pendingRequestsCounter > 0) {
                // we have some pending requests, so do something here 
            }
            return request;
        },
        response: function (response) {
            pendingRequestsCounter--;
            if (pendingRequestsCounter === 0) {
                // we have no pending requests, so do something else here 
            }
            return response;
       }
    };
}]);