Usage of $broadcast(), $emit() And $on() in AngularJS

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I understand that $Broadcast(), $Emit() And $On() are used to raise an event in one controller and handling in another controller. If possible, can someone just give me some real time example on the usage of above three as I am new to angular JS?

I have gone through the following links and understand the basic usage.

http://www.binaryintellect.net/articles/5d8be0b6-e294-457e-82b0-ba7cc10cae0e.aspx

This question is tagged with angularjs

~ Asked on 2016-06-09 05:26:52

The Best Answer is


123

$emit

It dispatches an event name upwards through the scope hierarchy and notify to the registered $rootScope.Scope listeners. The event life cycle starts at the scope on which $emit was called. The event traverses upwards toward the root scope and calls all registered listeners along the way. The event will stop propagating if one of the listeners cancels it.

$broadcast

It dispatches an event name downwards to all child scopes (and their children) and notify to the registered $rootScope.Scope listeners. The event life cycle starts at the scope on which $broadcast was called. All listeners for the event on this scope get notified. Afterwards, the event traverses downwards toward the child scopes and calls all registered listeners along the way. The event cannot be canceled.

$on

It listen on events of a given type. It can catch the event dispatched by $broadcast and $emit.


Visual demo:

Demo working code, visually showing scope tree (parent/child relationship):
http://plnkr.co/edit/am6IDw?p=preview

Demonstrates the method calls:

  $scope.$on('eventEmitedName', function(event, data) ...
  $scope.broadcastEvent
  $scope.emitEvent

~ Answered on 2016-06-09 05:40:23


21

  • Broadcast: We can pass the value from parent to child (i.e parent -> child controller.)
  • Emit: we can pass the value from child to parent (i.e.child ->parent controller.)
  • On: catch the event dispatched by $broadcast or $emit.

~ Answered on 2017-03-13 20:03:19


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