How to declare and use a enum variable in Javascript?

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What is the correct way to declare and use a enum variable, in Javascript?

Answer 1

Best Answer

Answer by duck · Apr 16, 2010 at 11:27 AM

Like this (using the example of various AI states for an AI State Machine):

enum AIState { Asleep, Idling, Chasing, Fleeing, HavingLunch }

And then you can assign any value from that enum to a variable, like this:

var state = AIState.Idling;

In the above example, the variable's type is implicitly defined as "AIState". You can explicitly define a variable with that type like this:

var state : AIState;

And similarly you can define the input parameter of a function to recieve a value from your enum, like this:

function PerformAction( currentState : AIState ) {

 switch (currentState) {
     case AIState.Asleep: 
         Debug.Log("Zzzz.");
         break;

     // etc...
 }

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· Jun 15, 2010 at 08:55 AM 1

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I've upvoted your answer because it helped me, but your example code is slightly incorrect. In the enum declaration, you've named it 'Asleep', but in the switch, you're checking for 'Sleeping'. Cheers.

duck ♦♦ · Jun 15, 2010 at 10:10 PM 0

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thanks for the pointer! just edited it to fix that.

RoxPhilosopher · May 18, 2011 at 11:51 PM 0

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Is it true that enum declarations have to be outside of a function?

Answer 2

Answer by Toxic Blob · Apr 13, 2011 at 02:03 PM

You can also assign values to your individual enum elements.

enum Layer
    {
    Protagonists    = 9,
    Antagonists     = 10,
    HeadsUpDisplay  = 11,
    LevelBoundaries = 13
    }

This is incredibly helpful if you use layers, for example. Rather than using

this.gameObject.layer = 9;

You could instead use the easier to read

this.gameObject.layer = Layer.Protagonists;

This is especially helpful as there is then only one location, your enum, where you have to change the layer number if a change is needed.

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sabliao · Oct 12, 2011 at 11:00 PM 0

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What would be the purpose of assigning them different layers? Is it one way to have another kind of differentiation? Such as only finding objects within a certain layer?

andyisbonza · Mar 30, 2014 at 06:52 AM 0

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That is a great tip - upvoted!

I use layers to stop objects from colliding with each other when I don't want them interacting. If, for example, you had an enemy that was unaffected by bullets, one option would be to put them on a different layer from each other, then ensure that the bullet's layer and the enemy's layer didn't cause collision (under Project settings --> Physics)

How to declare and use a enum variable in Javascript?

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