CODEWITHSUNDEEP
typescript
Qix - MONICA WAS MISTREATED
Qix - MONICA WAS MISTREATED

Reputation: 15113

Declare an `any` value as a class

There is a small, ad-hoc script I'm forced to require() (not import) and I want to wrap it in a typescript file with an adjacent declare class statement.

declare class MyCache<K, T> {
    constructor(numItems: number);
    get(key: K): T;
    set(key: K, val: T): void;
}

const Cache = require('./my-cache-module');
export default Cache as MyCache<K, T>; // <---- not quite right...

// intended to be used as:
//
//    const cache: MyCache<string, string> = new MyCache(100);
//    cache.set('foo', 'bar');
//    cache.get('foo'); //-> 'bar'

How do I tell Typescript that Cache is not an instance of MyCache, but is instead the actual implementation of the class?

Upvotes: 0

Views: 42

Answers (1)

Titian Cernicova-Dragomir
Titian Cernicova-Dragomir

Reputation: 250106

You need to type assert to typeof MyClass instead. The class name is the instance type and typeof Class is the type for the class itself.

 export default cache as typeof MyCache;

Upvotes: 1

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