# Object.update

## Function

Merge one or more objects into the current object in place.

## Syntax

```bt
object.update(source1, source2, ...)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| sourceN | Object | No | None | The source object to merge; non-object arguments are ignored. |

## Return value

| Type | Description |
| ------ | ------ |
| Object | Returns the original object to facilitate continued chain calls. |

## Return object fields

`update()` returns the same object reference that it was called on. The returned object first retains the original fields, and then writes the fields of each source object in parameter order; fields with the same name are overwritten by the source object written later.

## Example

```bt
config = {host: '127.0.0.1'}
config.update({port: 8080})

// Output: {"host":"127.0.0.1","port":8080}
echo(config)
```

## Notes

- update will modify the original object.
- update will refuse to write values that would create circular references.