Establish an enumeration using universally recognized identifiers

Question

Establish an enumeration using universally recognized identifiers

I have a JavaScript function that requires a numerical input, as well as some predefined constants at the top level:

var FOO = 1;
var BAR = 2;

The function should only be called using one of these constants.

To ensure type safety in TypeScript, I am attempting to create an interface using an enum:

declare enum MyType {
    FOO,
    BAR
}

interface MyClass {
    process(MyType type);
}

However, when the code is compiled, it outputs MyType.FOO in the JavaScript file. Is there a way to make it output just FOO while still maintaining type safety in TypeScript?

enums typescript

Answer 1

Answer №1

// Version X
const enum _YourType {
    APPLE,
    ORANGE
}
let APPLE = _YourType.APPLE;
let ORANGE = _YourType.ORANGE;

or

// Version Y (if APPLE and ORANGE are imported from another module)
declare const enum _YourType {
    APPLE,
    ORANGE
}
declare let APPLE: _YourType;
declare let ORANGE: _YourType;

Either way,

function myFunction(y: _YourType) { /* ... */ }

myFunction(APPLE); // OK
myFunction('banana'); // Error

Answer 2

// Version X
const enum _YourType {
    APPLE,
    ORANGE
}
let APPLE = _YourType.APPLE;
let ORANGE = _YourType.ORANGE;

or

// Version Y (if APPLE and ORANGE are imported from another module)
declare const enum _YourType {
    APPLE,
    ORANGE
}
declare let APPLE: _YourType;
declare let ORANGE: _YourType;

Either way,

function myFunction(y: _YourType) { /* ... */ }

myFunction(APPLE); // OK
myFunction('banana'); // Error

Establish an enumeration using universally recognized identifiers

Answer №1

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