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

# JSON.ARRAPPEND

> Append values to a JSON array

Appends one or more values to the end of a JSON array at the specified path.

## Usage

```typescript theme={null}
const newLength = await redis.json.arrappend("user:123", "$.tags", "premium", "verified");
```

## Arguments

<ParamField path="key" type="string" required>
  The key containing the JSON document
</ParamField>

<ParamField path="path" type="string" required>
  JSONPath expression pointing to the array to append to
</ParamField>

<ParamField path="values" type="...TData[]" required>
  One or more values to append to the array. Can be any JSON-serializable values.
</ParamField>

## Response

<ResponseField name="result" type="(number | null)[]">
  An array of numbers representing the new length of the array at each matching path. Returns `null` for paths that don't exist or aren't arrays.
</ResponseField>

## Examples

### Append single value to array

```typescript theme={null}
// Initial: { "tags": ["developer", "admin"] }
const newLength = await redis.json.arrappend("user:123", "$.tags", "premium");
console.log(newLength); // [3]

// Result: { "tags": ["developer", "admin", "premium"] }
```

### Append multiple values

```typescript theme={null}
const newLength = await redis.json.arrappend(
  "user:123",
  "$.tags",
  "verified",
  "active",
  "pro"
);
console.log(newLength); // [6]

// Result: { "tags": ["developer", "admin", "premium", "verified", "active", "pro"] }
```

### Append to nested array

```typescript theme={null}
interface Order {
  id: string;
  items: string[];
}

const newLength = await redis.json.arrappend(
  "order:456",
  "$.items",
  "item-123"
);
console.log(newLength); // [4]
```

### Append objects to array

```typescript theme={null}
interface Product {
  id: string;
  name: string;
  price: number;
}

const newProduct: Product = {
  id: "prod-789",
  name: "Widget",
  price: 29.99
};

const newLength = await redis.json.arrappend(
  "cart:123",
  "$.products",
  newProduct
);
```

### Append to multiple arrays (wildcard path)

```typescript theme={null}
// Initial: {
//   "users": [
//     { "id": 1, "tags": ["active"] },
//     { "id": 2, "tags": ["inactive"] }
//   ]
// }

const newLengths = await redis.json.arrappend(
  "data:1",
  "$.users[*].tags",
  "updated"
);
console.log(newLengths); // [2, 2]

// Result: Both users now have "updated" tag appended
```

### Handle non-existent paths

```typescript theme={null}
const newLength = await redis.json.arrappend(
  "user:123",
  "$.nonexistent",
  "value"
);
console.log(newLength); // [null]
```

## JSONPath Syntax

* `$.array` - Append to a top-level array
* `$.nested.array` - Append to a nested array
* `$.array[0].items` - Append to array within array element
* `$..array` - Append to all matching arrays recursively
* `$.items[*].tags` - Append to arrays within each item

## Notes

* The path must point to an existing array. If the path doesn't exist or points to a non-array value, `null` is returned for that path.
* When using wildcard paths, the operation is performed on all matching arrays.
* Values are automatically JSON-serialized before appending.

## See Also

* [JSON.ARRINDEX](/api/commands/json-arrindex) - Find index of value in array
* [JSON.SET](/api/commands/json-set) - Set JSON values
* [Redis JSON.ARRAPPEND documentation](https://redis.io/commands/json.arrappend)