elasticsearch-js/docs/reference/api/IngestLowercaseProcessor.md

IngestLowercaseProcessor [interface-IngestLowercaseProcessor]

Name	Type	Description
field	Field	The field to make lowercase.
ignore_missing	boolean	If true and field does not exist or is null, the processor quietly exits without modifying the document.
target_field	Field	The field to assign the converted value to. By default, the field is updated in-place.