HTML tutorial
CSS3 tutorial
Bootstrap tutorial
JavaScript tutorial
JQuery tutorial
AngularJS tutorial
React tutorial
NodeJS tutorial
PHP tutorial
Python tutorial
Python3 tutorial
Django tutorial
Linux tutorial
Docker tutorial
Ruby tutorial
Java tutorial
C tutorial
C ++ tutorial
Perl tutorial
JSP tutorial
Lua tutorial
Scala tutorial
Go tutorial
ASP.NET tutorial
C # tutorial
An enum is a special "class" that represents a group of constants (unchangeable variables)
By default, enums will initialize the first value to 0
and add 1 to each additional value:
enum CardinalDirections {
North,
East,
South,
West
}
let currentDirection = CardinalDirections.North;
// logs 0
console.log(currentDirection);
// throws error as 'North' is not a valid enum
currentDirection = 'North'; // Error: "North" is not assignable to type 'CardinalDirections'.
You can set the value of the first numeric enum and have it auto increment from that:
enum CardinalDirections {
North = 1,
East,
South,
West
}
// logs 1
console.log(CardinalDirections.North);
// logs 4
console.log(CardinalDirections.West);
You can assign unique number values for each enum value. Then the values will not incremented automatically:
enum StatusCodes {
NotFound = 404,
Success = 200,
Accepted = 202,
BadRequest = 400
}
// logs 404
console.log(StatusCodes.NotFound);
// logs 200
console.log(StatusCodes.Success);
Enums can also contain strings
. This is more common than numeric enums, because of their readability and intent.
enum CardinalDirections {
North = 'North',
East = "East",
South = "South",
West = "West"
};
// logs "North"
console.log(CardinalDirections.North);
// logs "West"
console.log(CardinalDirections.West);
Technically, you can mix and match string and numeric enum values, but it is recommended not to do so.