Check if value exists in enum in TypeScript

I recieve a number type = 3 and have to check if it exists in this enum:

export const MESSAGE_TYPE = {
    INFO: 1,
    SUCCESS: 2,
    WARNING: 3,
    ERROR: 4,
};

The best way I found is by getting all Enum Values as an array and using indexOf on it. But the resulting code isn't very legible:

if( -1 < _.values( MESSAGE_TYPE ).indexOf( _.toInteger( type ) ) ) {
    // do stuff ...
}

Is there a simpler way of doing this?

Answers:

Answer

If you want this to work with string enums, you need to use Object.values(ENUM).includes(ENUM.value) because string enums are not reverse mapped, according to https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-4.html:

Enum Vehicle {
    Car = 'car',
    Bike = 'bike',
    Truck = 'truck'
}

becomes:

{
    Car: 'car',
    Bike: 'bike',
    Truck: 'truck'
}

So you just need to do:

if (Object.values(Vehicle).includes('car')) {
    // Do stuff here
}

If you get an error for: Property 'values' does not exist on type 'ObjectConstructor', then you are not targeting ES2017. You can either use this tsconfig.json config:

"compilerOptions": {
    "lib": ["es2017"]
}

Or you can just do an any cast:

if ((<any>Object).values(Vehicle).includes('car')) {
    // Do stuff here
}
Answer

If you are using TypeScript, you can use an actual enum. Then you can check it using in.

This works only if your enum is number-based and not marked const:

export enum MESSAGE_TYPE {
    INFO = 1,
    SUCCESS = 2,
    WARNING = 3,
    ERROR = 4,
};

var type = 3;

if (type in MESSAGE_TYPE) {

}

This works because when you compile the above enum, it generates the below object:

{
    '1': 'INFO',
    '2': 'SUCCESS',
    '3': 'WARNING',
    '4': 'ERROR',
    INFO: 1,
    SUCCESS: 2,
    WARNING: 3,
    ERROR: 4
}
Answer

There is a very simple and easy solution to your question:

var districtId = 210;

if (DistrictsEnum[districtId] != null) {

// Returns 'undefined' if the districtId not exists in the DistrictsEnum 
    model.handlingDistrictId = districtId;
}
Answer

TypeScript v3.7.3

export enum YourEnum {
   enum1 = 'enum1',
   enum2 = 'enum2',
   enum3 = 'enum3',
}

const status = 'enumnumnum';

if (!(status in YourEnum)) {
     throw new UnprocessableEntityResponse('Invalid enum val');
}
Answer
export enum UserLevel {
  Staff = 0,
  Leader,
  Manager,
}

export enum Gender {
  None = "none",
  Male = "male",
  Female = "female",
}

Difference result in log:

log(Object.keys(Gender))
=>
[ 'None', 'Male', 'Female' ]

log(Object.keys(UserLevel))
=>
[ '0', '1', '2', 'Staff', 'Leader', 'Manager' ]

The solution, we need to remove key as a number.

export class Util {
  static existValueInEnum(type: any, value: any): boolean {
    return Object.keys(type).filter(k => isNaN(Number(k))).filter(k => type[k] === value).length > 0;
  }
}

Usage

// For string value
if (!Util.existValueInEnum(Gender, "XYZ")) {
  //todo
}

//For number value, remember cast to Number using Number(val)
if (!Util.existValueInEnum(UserLevel, 0)) {
  //todo
}
Answer

As per Ryan Cavanaugh's answer, you can simply do the following to check if a value is contained in a given enum:

if ('value4' in someEnum) {
  // ...
}
Answer
enum ServicePlatform {
    UPLAY = "uplay",
    PSN = "psn",
    XBL = "xbl"
}

becomes:

{ UPLAY: 'uplay', PSN: 'psn', XBL: 'xbl' }

so

ServicePlatform.UPLAY in ServicePlatform // false

SOLUTION:

ServicePlatform.UPLAY.toUpperCase() in ServicePlatform // true

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