> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/supermacro/neverthrow/llms.txt
> Use this file to discover all available pages before exploring further.

# ResultAsync.orElse

> Recover from errors in a ResultAsync

## Overview

Handles the `Err` case of a `ResultAsync` by applying a recovery function. Useful for error recovery, fallbacks, and error transformation.

## Signature

```typescript theme={null}
class ResultAsync<T, E> {
  orElse<U, A>(
    f: (e: E) => Result<U, A> | ResultAsync<U, A>
  ): ResultAsync<U | T, A>
}
```

<ParamField path="f" type="(e: E) => Result<U, A> | ResultAsync<U, A>" required>
  Function that takes the Err value and returns a new Result or ResultAsync
</ParamField>

**Returns:** `ResultAsync<U | T, A>` - A ResultAsync with potentially recovered value

## Usage

### Simple fallback

```typescript theme={null}
const result = await fetchFromCache(key)
  .orElse(() => fetchFromDatabase(key))
  .orElse(() => okAsync(defaultValue))

// Tries cache, then database, then default
```

### Conditional recovery

```typescript theme={null}
type ApiError = { code: number, message: string }

const result = await callApi()
  .orElse((error: ApiError) => {
    if (error.code === 404) {
      return okAsync(null) // Treat 404 as empty result
    }
    if (error.code === 503) {
      return retryAfterDelay() // Retry on service unavailable
    }
    return errAsync(error) // Propagate other errors
  })
```

### Multi-tier fallback

```typescript theme={null}
const loadConfig = () => {
  return readFromFile('./config.json')
    .orElse(() => readFromFile('./config.default.json'))
    .orElse(() => fetchFromRemote())
    .orElse(() => okAsync(HARDCODED_DEFAULTS))
}
```

## Key characteristics

* **Only runs on Err**: If the ResultAsync is Ok, orElse is not executed
* **Can change type**: The recovery function can return a different value type
* **Error type changes**: The new error type replaces the original

<Tip>
  Use `orElse` to implement graceful degradation in your async operations.
</Tip>

## Related

<CardGroup cols={2}>
  <Card title="andThen" icon="link" href="./and-then">
    Chain successful operations
  </Card>

  <Card title="unwrapOr" icon="gift" href="./unwrap-or">
    Provide a simple default value
  </Card>
</CardGroup>