Types with different parameters like function overload-CodePudding

I'm trying to write a type which acts as a function signature that allows to have to different set of parameters:

The first case, the function expects a predicate.
The second case, the function expects two parameters.

This is the example:

I'm pretty sure this can be done because we have the function overload, but I've been able to use them only inside a class. But it's basically the same thing, expect in this case I'm defining the method as a global variable.

CodePudding user response：

Use an interface to describe a set of call signatures:

interface TCommon<TEntity> {
    (predicate: ((entity: TEntity) => TEntity | void)): void
    (propertyName: keyof TEntity, newValue: unknown): void;
}

But we aren't quite done yet. The second parameter is optional in the sense that the first overload doesn't need a second parameter but the second overload does.

So we mark the second parameter as optional:

const method: TCommon<IEntity> = (param1, param2?: unknown) => {

And that's it.

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