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Table of contents
1. Typescript String-based Enums
// Example 2 - String-based Enums
enum Direction {
Up = "UP",
Down = "DOWN",
Left = "LEFT",
Right = "RIGHT",
}
1.1 Typescript String-based Enums Examples
Example 1: How to create enum in Typescript
// 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
console.log(Direction.Up);
console.log(Direction.Down);
console.log(Direction['Up']);
console.log(Direction['Down']);
c:\user\typescript-tutorial> tsc .\enums.ts
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']);
c:\user\typescript-tutorial> node .\enums.js
UP
DOWN
LEFT
RIGHT
UP
DOWN
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
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);
C:\user\typescript-tutorial> tsc .\enums.js
C:\user\typescript-tutorial> node .\enums.js
UP
DOWN
LEFT
RIGHT
2. Traditional Number-based Enums
2.1 Example: How to create number-based enums
enum Weekday {
Monday,
Tuesday,
Wednesday,
Thursday,
Friday,
Saturday,
Sunday
}
// Access enum member values
console.log(Weekday.Sunday);
console.log(Weekday['Sunday']);
console.log(Weekday[0]);
C:\user\typescript-tutorial> tsc .\enums.js
C:\user\typescript-tutorial> node .\enums.js
6
6
Monday
2.2 Access enum member values
// Access enum member values
console.log(Weekday.Sunday);
console.log(Weekday['Sunday']);
console.log(Weekday[0]);
enum Weekday {
Monday = 1,
Tuesday ,
Wednesday,
Thursday,
Friday,
Saturday,
Sunday
}
2.3 Enum as a function argument
enum Weekday {
Monday,
Tuesday,
Wednesday,
Thursday,
Friday,
Saturday,
Sunday
}
function test(weekday: Weekday){
console.log(weekday);
}
test(Weekday.Sunday);
test(Weekday.Monday);
3. Heterogeneous enum
enum BooleanLikeHeterogeneousEnum {
No = 0,
Yes = "YES",
}
4. Typescript const enums
const enum Direction {
Up = "UP",
Down = "DOWN",
Left = "LEFT",
Right = "RIGHT",
}
5. Enum with static functions
enum Weekday {
Monday,
Tuesday,
Wednesday,
Thursday,
Friday,
Saturday,
Sunday
}
namespace Weekday {
export function isBusinessDay(day: Weekday) {
switch (day) {
case Weekday.Saturday:
case Weekday.Sunday:
return false;
default:
return true;
}
}
}
const mon = Weekday.Monday;
const sun = Weekday.Sunday;
console.log(Weekday.isBusinessDay(mon)); // true
console.log(Weekday.isBusinessDay(sun)); // false
Most useful Typescript enums examples. Recommended tutorial.
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