How can I guarantee that my enums definition doesn't change in JavaScript?

Question

Would the following make the objects fulfil all characteristics that enums have in JavaScript? Something like:

my.namespace.ColorEnum = {   RED : 0,   GREEN : 1,   BLUE : 2 }  // later on  if(currentColor == my.namespace.ColorEnum.RED) {   // whatever }  

Or is there some other way I can do this?

Answer 1

Since 1.8.5 it's possible to seal and freeze the object, so define the above as:

const DaysEnum = Object.freeze({"monday":1, "tuesday":2, "wednesday":3, ...}) 

or

const DaysEnum = {"monday":1, "tuesday":2, "wednesday":3, ...} Object.freeze(DaysEnum) 

and voila! JS enums.

However, this doesn't prevent you from assigning an undesired value to a variable, which is often the main goal of enums:

let day = DaysEnum.tuesday day = 298832342 // goes through without any errors 

One way to ensure a stronger degree of type safety (with enums or otherwise) is to use a tool like TypeScript or Flow.

Quotes aren't needed but I kept them for consistency.

Answer 2

This isn't much of an answer, but I'd say that works just fine, personally

Having said that, since it doesn't matter what the values are (you've used 0, 1, 2), I'd use a meaningful string in case you ever wanted to output the current value.