Question

我正在阅读catchError的源代码。我注意到它的定义如下：似乎它将一个带有两个参数并返回Observable-selector: (err: any, caught: Observable<T>) => ObservableInput<R>

的函数作为参数。

export function catchError<T>(selector: (err: any, caught: Observable<T>) => never): MonoTypeOperatorFunction<T>;
export function catchError<T, R>(selector: (err: any, caught: Observable<T>) => ObservableInput<R>): OperatorFunction<T, T | R>;
export function catchError<T, R>(selector: (err: any, caught: Observable<T>) => ObservableInput<R>): OperatorFunction<T, T | R> {
  return function catchErrorOperatorFunction(source: Observable<T>): Observable<T | R> {
    const operator = new CatchOperator(selector);
    const caught = source.lift(operator);
    return (operator.caught = caught as Observable<T>);
  };
}

但是在使用catchError的示例中，似乎采用了带有一个参数catchError(err => of[])的函数。这些示例为什么不需要第二个参数caught？

catchError似乎需要两个参数而不是一个

0 个答案: