Why avoid using $rootScope.$broadcast() and use $rootScope.$emit() instead

[bonsai]

The product documentation below states that you should avoid using "$rootScope.$broadcast()" and use "$rootScope.$emit()" instead.
Why is this?

I understand that these are used to pass values ​​between widgets.

https://www.servicenow.com/docs/bundle/yokohama-application-development/page/build/professional-deve...

[RaghavSh]

It has performance issues.

[Bhimashankar H · Accepted solution]

Hi @bonsai ,

The recommendation to prefer $rootScope.$emit() over $rootScope.$broadcast() in AngularJS (which ServiceNow Service Portal uses) relates to how events propagate through the scope hierarchy and the impact on performance and maintain.

$rootScope.$broadcast()	Downwards from root to all child scopes
$rootScope.$emit()	Upwards from root scope (rarely used at root)

$broadcast() sends the event to every child scope in the app, which may be many scopes, potentially causing unnecessary listeners to execute and slowing down the app performance and speed.

$emit() propagates the event upwards through parent scopes, which is usually more targeted.  With $rootScope.$emit(), event listeners explicitly on $rootScope or its ancestors receive it, reducing noise.

Thanks,
Bhimashankar H

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