I am facing a challenge with incorporating a knockout extender into a typescript file, struggling to properly declare it.
The extender is in javascript, and I need to utilize it from within a typescript file (as the project consists of both javascript and typescript). However, defining the extender has been elusive. Referencing this question, I attempted to enhance the KnockoutExtenders interface as shown below:
interface KnockoutExtenders {
trackChange<T>(target: T, track: boolean): ITrackChange<T>;
}
interface ITrackChange<T> extends KnockoutObservable<T> {
setOriginalValue(startingValue: T): void;
resetToConfirmedValue(): void;
setConfirmedValue(): void;
numberChanges(): number;
}
The usage of the extender follows this structure:
class ProductTypeViewModel {
constructor() {
this.name.setOriginalValue('Initial value');
}
name = ko.observable('').extend({
trackChange: true
});
}
An error arises during compilation stating that this.name.setOriginalValue does not exist on type 'KnockoutObservable<string>', which is correct.
How should I define the extender so that typescript recognizes the additional methods applied to the observable (transforming it from a KnockoutObservable<string> to an ITrackChange<string>)?
(While perhaps not vital, here is a brief explanation of the extender: The extender tracks changes made to an observable, providing the option to accept or cancel them. This allows for displaying a current value using the observable, while enabling users to edit the value without actually changing it until they confirm the modifications. If changes are canceled, no actual alterations occur.)