NodeRedis/node-redis

# Command Options

> :warning: The command options API in v5 has breaking changes from the previous version. For more details, refer to the [v4-to-v5 guide](./v4-to-v5.md#command-options).

Command Options are used to create "proxy clients" that change the behavior of executed commands. See the sections below for details.

## Type Mapping

Some [RESP types](./RESP.md) can be mapped to more than one JavaScript type. For example, "Blob String" can be mapped to `string` or `Buffer`. You can override the default type mapping using the `withTypeMapping` function:

```javascript
await client.get('key'); // `string | null`

const proxyClient = client.withTypeMapping({
  [TYPES.BLOB_STRING]: Buffer
});

await proxyClient.get('key'); // `Buffer | null`
```

See [RESP](./RESP.md) for a full list of types.

## Abort Signal

The client [batches commands](./FAQ.md#how-are-commands-batched) before sending them to Redis. Commands that haven't been written to the socket yet can be aborted using the [`AbortSignal`](https://developer.mozilla.org/en-US/docs/Web/API/AbortSignal) API:

```javascript
const controller = new AbortController(),
  client = client.withAbortSignal(controller.signal);

try {
  const promise = client.get('key');
  controller.abort();
  await promise;
} catch (err) {
  // AbortError
}
```

## ASAP

Commands that are executed in the "asap" mode are added to the beginning of the "to sent" queue.

```javascript
const asapClient = client.asap();
await asapClient.ping();
```

## `withCommandOptions`

You can set all of the above command options in a single call with the `withCommandOptions` function:

```javascript
client.withCommandOptions({
  typeMapping: ...,
  abortSignal: ...,
  asap: ...
});
```

If any of the above options are omitted, the default value will be used. For example, the following client would **not** be in ASAP mode:

```javascript
client.asap().withCommandOptions({
  typeMapping: ...,
  abortSignal: ...
});
```