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Function: tapErr()

Call Signature​

tapErr<T, E>(result, fn): Result<T, E>

Defined in: result/tap/index.ts:75

Performs a side effect with the Err value without modifying the Result.

Useful for error logging or monitoring while keeping the error flowing through the pipeline.

Type Parameters​

T​

T

E​

E

Parameters​

result​

Result<T, E>

The Result to tap into

fn​

(error) => void

Side effect function to call with the Err value

Returns​

Result<T, E>

The original Result unchanged

Example​

// Data-first
tapErr(ok(42), e => console.error(e)) // no log, returns Ok(42)
tapErr(err('fail'), e => console.error('Error:', e)) // logs, returns Err('fail')

// Data-last (in pipe) - error monitoring
pipe(
  parseConfig(str),
  tapErr(error => {
    logError(error)
    sendToMonitoring(error)
  }),
  mapErr(error => 'Using default config due to error'),
  unwrapOr(defaultConfig)
)

See​

tap - for side effects with Ok values

Call Signature​

tapErr<E>(fn): <T>(result) => Result<T, E>

Defined in: result/tap/index.ts:76

Performs a side effect with the Err value without modifying the Result.

Useful for error logging or monitoring while keeping the error flowing through the pipeline.

Type Parameters​

E​

E

Parameters​

fn​

(error) => void

Side effect function to call with the Err value

Returns​

The original Result unchanged

<T>(result): Result<T, E>

Type Parameters​

T​

T

Parameters​

result​

Result<T, E>

Returns​

Result<T, E>

Example​

// Data-first
tapErr(ok(42), e => console.error(e)) // no log, returns Ok(42)
tapErr(err('fail'), e => console.error('Error:', e)) // logs, returns Err('fail')

// Data-last (in pipe) - error monitoring
pipe(
  parseConfig(str),
  tapErr(error => {
    logError(error)
    sendToMonitoring(error)
  }),
  mapErr(error => 'Using default config due to error'),
  unwrapOr(defaultConfig)
)

See​

tap - for side effects with Ok values