# Array.join

## Function

Concatenate array elements into a string according to delimiters.

## Syntax

```bt
array.join(separator)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| separator | Any | No | "," | The separator between elements, which will be converted to a string first when called. |

## Return value

| Type | Description |
| ------ | ------ |
| String | Returns the concatenated string. |

## Example

```bt
items = ['BT', 'Lang']
result = items.join('-')

// Output: BT-Lang
print result
```

## Notes

- Each element will be converted to text according to BT stringification rules.