What is an eager property which is used to initialize the eager services. injector.eager()

[Hari]

I was going through the documentation and have the above question.
In anguarjs documentation of injector, it talks about eager service. I
am not quite sure what this means. If some one can explain this, I
would appreciate it ...

[Dan Doyon]

Taking from the ng doc, below is a non-eager service, basically, angular will not create this service until it is called the first time. So could you have a bunch of services defined but  only the ones you are actually using are created, you don't incur the cost of them until you use them. On the other hand adding a $eager: true attribute in the properties object so {$inject: ['$window'], $eager: true},  tells angular that this is a service you want loaded right away because your controllers or other services will depend on it being available.  Examples of where you would want to be eager might be a routing service or logging service. 

angular.module.ng('notify', function(win) {

  var msgs = [];

  return function(msg) {

    msgs.push(msg);

    if (msgs.length == 3) {

      win.alert(msgs.join("\n"));

      msgs = [];

    }

  };

}, {$inject: ['$window']});

--dan

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[Vojta Jina]

Yep, Dan is right:

- eager services are instantiated at the very beginning (when app is being bootstrap)

- non-eager services are instantiated only when needed, so if your code does not ask for non-eager service, it will never be instantiated

Btw, don't worry about it, we are getting rid off "eager" :-D

V.

[Luke Bayes]

Hey Guys,

Just following up on this thread.

Did you wind up getting rid of $eager?

We're about to need it for a KeyService.

We'd like to track DOM key events on the $document element, but then emit them something like the following pseudocode:

$window.document.addEventListener('keyup', function(domEvent) {

  var activeElement = $window.document.activeElement;

  var currentScope = activeElement ? angular.element(activeElement).scope() : $route.current.scope;

  currentScope.$emit(domEvent.name, domEvent);

});

This will give our controllers and other nested scopes the ability to handle key events and consider cancelling them if necessary.

But we'd rather not just inject this service into some arbitrary feature in order to instantiate it.

Please let us know.

Thanks,

Luke Bayes

[Vojta Jina]

Hey Luke, yep, eagers are gone.

But modules have a run method, where you can do this kind of stuff.

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

app.run(function($window) {

  angular.element($window).bind('keyup', function() {

    // ....

  });

});

V.