Check if value exists in enum in TypeScript

Question

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?

Answer 1

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 }