# Array.to_string

## Function

Serialize an array into a JSON string.

## Syntax

```bt
array.to_string(mode)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| mode | String | No | None | Returns the indentation format when passing in JSON_PRETTY. |

## Return value

| Type | Description |
| ------ | ------ |
| String | Returns an array of JSON strings. |

## Example

```bt
items = [1, 'BT']
result = items.to_string()

// Output: [1,"BT"]
print result
```

## Notes

- Normal mode outputs compact JSON.
- JSON_PRETTY is a system constant whose value is the string JSON_PRETTY.