How to create enum like type in TypeScript?
As of TypeScript 0.9 (currently an alpha release) you can use the enum definition like this:
enum TShirtSize {
Small,
Medium,
Large
}
var mySize = TShirtSize.Large;
By default, these enumerations will be assigned 0, 1 and 2 respectively. If you want to explicitly set these numbers, you can do so as part of the enum declaration.
Listing 6.2 Enumerations with explicit members
enum TShirtSize {
Small = 3,
Medium = 5,
Large = 8
}
var mySize = TShirtSize.Large;
Both of these examples lifted directly out of TypeScript for JavaScript Programmers.
Note that this is different to the 0.8 specification. The 0.8 specification looked like this - but it was marked as experimental and likely to change, so you'll have to update any old code:
Disclaimer - this 0.8 example would be broken in newer versions of the TypeScript compiler.
enum TShirtSize {
Small: 3,
Medium: 5,
Large: 8
}
var mySize = TShirtSize.Large;
TypeScript 0.9+ has a specification for enums:
enum AnimationType {
BOUNCE,
DROP,
}
The final comma is optional.
This is now part of the language. See TypeScriptLang.org > Basic Types > enum for the documentation on this. An excerpt from the documentation on how to use these enums:
enum Color {Red, Green, Blue};
var c: Color = Color.Green;
Or with manual backing numbers:
enum Color {Red = 1, Green = 2, Blue = 4};
var c: Color = Color.Green;
You can also go back to the enum name by using for example Color[2]
.
Here's an example of how this all goes together:
module myModule {
export enum Color {Red, Green, Blue};
export class MyClass {
myColor: Color;
constructor() {
console.log(this.myColor);
this.myColor = Color.Blue;
console.log(this.myColor);
console.log(Color[this.myColor]);
}
}
}
var foo = new myModule.MyClass();
This will log:
undefined 2 Blue
Because, at the time of writing this, the Typescript Playground will generate this code:
var myModule;
(function (myModule) {
(function (Color) {
Color[Color["Red"] = 0] = "Red";
Color[Color["Green"] = 1] = "Green";
Color[Color["Blue"] = 2] = "Blue";
})(myModule.Color || (myModule.Color = {}));
var Color = myModule.Color;
;
var MyClass = (function () {
function MyClass() {
console.log(this.myColor);
this.myColor = Color.Blue;
console.log(this.myColor);
console.log(Color[this.myColor]);
}
return MyClass;
})();
myModule.MyClass = MyClass;
})(myModule || (myModule = {}));
var foo = new myModule.MyClass();