Issue
Can someone explain me why the error instanceof CustomError
part of below code is false
?
class CustomError extends Error {}
const error = new CustomError();
console.log(error instanceof Error); // true
console.log(error instanceof CustomError); // false ???
class ParentClass {}
class ChildClass extends ParentClass { }
const child = new ChildClass();
console.log(child instanceof ParentClass); // true
console.log(child instanceof ChildClass); // true
Is something special about Error object? I would like to make my own error types that i can check against.
Btw i've checked the above code on latest TypeScript Playground
Solution
Turns out an change has been introduced in TypeScript@2.1 that breaks this pattern. The whole breaking change is described here.
In general it seems it's too complicated/error to even go with this direction.
Probably better to have own error object and keeps some original Error
as an property:
class CustomError {
originalError: Error;
constructor(originalError?: Error) {
if (originalError) {
this.originalError = originalError
}
}
}
class SpecificError extends CustomError {}
const error = new SpecificError(new Error('test'));
console.log(error instanceof CustomError); // true
console.log(error instanceof SpecificError); // true
Answered By - Adam Szmyd
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