Module "operators/throw-if-undefined"

throwIfUndefined

• throwIfUndefined<T>(errorFn: (value: T, index: number) => any): OperatorFunction<T, Exclude<T, undefined>>

• Throws the error built by errorFn if the current value is undefined. Performs type narrowing and removes undefined from your value type.

  example

  const input = of(value as string | undefined);
  
  const result = input.pipe(
    map(v => v) // typeof v = string | undefined
    throwIfUndefined(() => 'error'),
    map(v => v) // typeof v = string
  );

  Type parameters

  • T

  Parameters

  • errorFn: (value: T, index: number) => any

    Evaluates to the error which can be thrown.

    • • (value: T, index: number): any

      • Parameters

        • value: T

        • index: number

        Returns any

  Returns OperatorFunction<T, Exclude<T, undefined>>