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Listen to window events in an Angularjs service

Posted by: admin January 30, 2018 Leave a comment

Questions:

I want to listen to the window events in my AngularJS service so that I can broadcast them to my controllers.

I have a Chrome extension which sends any message using port.postMessage('Any Message');.

I want my angularjs service to listen to that message and send it to the controller using $rootScope.$broadcast("Something occurred.");

Inside my service, I am trying to do so with the following listener.

window.addEventListener('Any Message', function (event) {
    if (event.origin != window.location.origin) {
        return;
    }
    $rootScope.$broadcast("Something occurred.");
});

I also tried $window but I don’t know why the above code does not work. Also my IDE, jetbrains webstorms classify above code snippet as unreachable.

Before this, I used the above code in a controller and it worked fine. I wasn’t doing broadcast in controller. Now I want to move this to the service so that all controllers should be able to listen to it from service.

Answers:

Here is working example I’ve made – with subscribing DOM event and broadcasting the event from service to controller: http://plnkr.co/edit/nk2aPt?p=preview

//this is service that creates subscription    
app.service('serviceName', function($window, $rootScope) {

      function subsFunc() {
        $window.addEventListener('click', function(e) {
          $rootScope.$broadcast('app.clickEvent', e);
        })
      }

      return {
        "subscribeMe": subsFunc      }
    });

//this will be in controller
  $rootScope.$on('app.clickEvent', function(a, b) {
    //a,b - event object details
  });

Questions:
Answers:

Something like this might help:

var app = angular.module('app', []);

app.run(["$window", "$rootScope", function($window, $rootScope) {

    $window.addEventListener('message', function(e) {

        $rootScope.$broadcast('message', e.data);
    });
} ]);

Questions:
Answers:

Do you inject that service somewhere? Services will run only if you really injects them.

Additionally, it’s better to use $window instead of window, so you’ll be able to mock it later in your tests.

Questions:
Answers:

Problem:

"$window listener" listen multiple time. 

Example:

Consider , we wrote a listener code in Page B. My starting page is Page A.

I added an alert in listener code in Page B.

$window.addEventListener('message', function (e) { alert() }); 

Lets Go,

  • Page A >> Page B (alert count 1) Page B >> Page A >> Page B (alert
    count 2) Page B >> Page A >> Page B (alert count 3)