Which is more 'expensive'? $watch or $emit/$on in AngularJS?

Question

Really, I have a dilemma - and I'm sure I'm not the only one. Sometimes I'm conflicted between using $emit/$on communication, and just $watch on a scope to fire events. I am sure the answer is something like "depends on how many listeners etc." - but was wondering if 1:1 there was a better practice?

Answer 1

The concept of both are different. So the question title Which is more 'expensive'? $watch or $emit/$on in AngularJS? is not useful as if it is expensive or not.

You can see the documentation in more details.

watch:

Registers a listener callback to be executed whenever the watchExpression changes.

on:

Listens on events of a given type.

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So, the watch is used to consider if the variable or object is going to change? Then apply it.

And the on method is used to consider sharing event between each-other. So from parent you can broadcast the event and the child can emit the broadcasted event.

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You may also be interested the followings:

watch and apply

working with on

broadcast vs emit