CODEWITHSUNDEEP
javascripttypescript
nehalist
nehalist

Reputation: 1496

Extending classes with decorators in TypeScript

I'd like to extend a class with decorators but don't know how exactly. My current approach is as follows:

function Foo(value: string) {
    return function(target: Function) {
        let injected = Object.assign(target.prototype, { foo: value });
        return injected;
    }
}

@Foo("Hello world")
class Bar {
}

let instance = new Bar();
console.log(instance.foo); // Should say "Hello World"

But I can't instantiate my class anymore: "TypeError: Bar is not a constructor".

Where's my mistake?

Upvotes: 2

Views: 3370

Answers (1)

Nikolay Osaulenko
Nikolay Osaulenko

Reputation: 1482

You don't have to return a new object from the decorator. In this case target object will be modified, so just

function Foo(value: string) {
  return function(target: Function) {
    Object.assign(target.prototype, { foo: value });
  }
}

should work fine

Upvotes: 1

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