TypeScript Enum with String Values

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In this example shows how to create and use TypeScript string enums with examples.

In TypeScript, enums are set of named constants. Though it is optional, enums should be a named group of related constants. 

Typescript String-based Enums

In a string enum, each member has to be constant-initialized with a string literal, or with another string enum member.

Check out enums in Java at Java Enums Tutorial.

Enum syntax is very similar to other languages e.g. Java.

// Example 2 - String-based Enums enum Direction { Up = "UP", Down = "DOWN", Left = "LEFT", Right = "RIGHT", }

Typescript String-based Enums Examples

Example 1: How to create String-based enum in Typescript

Let's create a typescript file named enums.ts and add following code to it:

// Example 2 - String-based Enums enum Direction { Up = "UP", Down = "DOWN", Left = "LEFT", Right = "RIGHT", } // Access enum member values console.log(Direction.Up); console.log(Direction.Down); console.log(Direction.Left); console.log(Direction.Right); console.log(Direction['Up']); console.log(Direction['Down']);

Example 2: How to access enum member values

Use Enum.member or Enum['member'] format to access enum member values. For Example:

console.log(Direction.Up); console.log(Direction.Down); console.log(Direction['Up']); console.log(Direction['Down']);

Let's run above typescript file using the following command:

c:\user\typescript-tutorial> tsc .\enums.ts 

Look at the generated code in JavaScript. It has a generated lookup table like this.

var Direction; (function (Direction) { Direction["Up"] = "UP"; Direction["Down"] = "DOWN"; Direction["Left"] = "LEFT"; Direction["Right"] = "RIGHT"; })(Direction || (Direction = {})); // Access enum member values console.log(Direction.Up); console.log(Direction.Down); console.log(Direction.Left); console.log(Direction.Right); console.log(Direction['Up']); console.log(Direction['Down']);

The above file created as enums.js file. Now we don't need a browser, we can use node.js to run this javascript file. Let's run this enums.js file using the following command:

c:\user\typescript-tutorial> node .\enums.js UP DOWN LEFT RIGHT UP DOWN 

Follow similar steps to run below typescript examples.

Example 3: LogLevel Enum

// Example 1- String-based Enums export enum LogLevel { Off = "Off", Fatal = "Fatal", Error = "Error", Warn = "Warn", Info = "Info", Debug = "Debug" } // Access enum member values console.log(LogLevel.Debug); console.log(LogLevel.Error); console.log(LogLevel.Warn); console.log(LogLevel.Info); console.log(LogLevel.Fatal); console.log(LogLevel['Fatal']); console.log(LogLevel['Debug']); console.log(LogLevel['Info']);

Example 4: Weekday Enum

// Example 3 - String-based Enums enum Weekday { Monday = "Monday", Tuesday = "Tuesday", Wednesday = "Wednesday", Thursday = "Thursday", Friday = "Friday", Saturday = "Saturday", Sunday = "Sunday" } // Access enum member values console.log(Weekday.Monday); console.log(Weekday.Tuesday); console.log(Weekday.Wednesday); console.log(Weekday.Thursday); console.log(Weekday.Friday); console.log(Weekday.Saturday); console.log(Weekday.Sunday); console.log(Weekday['Saturday']); console.log(Weekday['Sunday']);

Example 5: Enum as a function argument

To pass enum in functions, declare the argument type of enum itself.

enum Direction { Up = "UP", Down = "DOWN", Left = "LEFT", Right = "RIGHT", } function checkDirection(direction: Direction){ console.log(direction); } checkDirection(Direction.Up); checkDirection(Direction.Down); checkDirection(Direction.Left); checkDirection(Direction.Right);

Output:

C:\user\typescript-tutorial> tsc .\enums.js C:\user\typescript-tutorial> node .\enums.js UP DOWN LEFT RIGHT

Learn more about TypeScript at TypeScript Tutorial with Examples.