Use Enum as restricted key type in Typescript

Question

The question is can enum be used as a key type instead of only "number" or "string" ? Currently it seems like the only possible declaration is x:{[key:number]:any} where key can be of type "number" or "string". Is it possible to make something like in this example:

Example:

enum MyEnum {     First,     Second }  var layer:{[key:MyEnum]:any}; 

Answer 1

Since 2018, there is an easier way in Typescript, without using keyof typeof:

let layer: { [key in MyEnum]: any} 

To not have to include all keys:

let layer: { [key in MyEnum]?: any} 

Answer 2

Yes. Just type

let layer:{[key in keyof typeof MyEnum]: any} 

The keyof keyword is available since Typescript 2.1. See the TypeScript documentation for more details. Using only keyof for enums wouldn't work (you'd get the keys of the enum type and not the enum constants), so you have to type keyof typeof.