Basics

enum VehicleType {
 PedalCycle,
 MotorCycle,
 Car,
 Van,
 Bus,
 Lorry
}

• Enumerations represent a collection of named elements that you can use to avoid littering your program with hard-coded values.
• By default, enumerations are zero based although you can change this by specifying the first value, in which case numbers will increment from value you set.
• You can opt to specify values for all identifiers if you wish to too.

Emum with string

 enum CardinalDirections {
  North = 'North',
  East = "East",
  South = "South",
  West = "West"
};
// logs "North"
console.log(CardinalDirections.North);
// logs "West"
console.log(CardinalDirections.West);

Const enum

const enum Light {
    Red,
    Green,
    Blue
}

• const enum references are replaced by inline codes. For example, console.log(Light.Red) is compiled as console.log(0 /* Red */).
• Because there is no JavaScript object that associates with const enum is generated at run time, it is not possible to loop over the const enum values.