Prevent TypeScript public function calling a private function

user_1058671 0
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I have this class:

export class ResourceFactory {
    AlgoliaAppId = "AlgoliaAppId";
    // ...

    private resetParams() {
        this.AlgoliaAppId = "AlgoliaAppId";
        // ...
    }

    public initTemplate(objectName, directiveArgs): Template {
        this.resetParams();  // <-- Can I, in any possible way, prevent this line from running?

        this.AlgoliaAppId = `${this.AlgoliaAppId}${objectName}`;
        // ... [long function content which I don't want to duplicate]
    }
}

I'm trying to extend the ResourceFactory class: I want to change the AlgoliaAppId name and prevent resetParams from running. (I cannot edit the original class).

Is there any way to override resetParams even though it's private, or at least somehow monkey-patch the initTemplate method so it won't run the line this.resetParams?

typescript monkeypatching oop javascript
1 Answers

There's no (clean) way to override a private method from a base class you don't have control over. I tried some module augmentation to see if I could change the modifier to protected but didn't have much luck; TypeScript seems to want all overloads to have the same modifier.

However, I was able to patch the prototype after the class declaration to hack in an overload, at the cost of including a @ts-expect-error comment. Seems to be the path of least resistance for fighting with the compiler. Here's what an example subclass would look like:

class Example extends ResourceFactory {
    AlgoliaAppId = "CustomName";
}

// @ts-expect-error
Example.prototype.resetParams = function resetParams() { 
    // your implementation
}

Here's a link to the playground as well.

user_92771320
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