Use CodeCompletion in undefined file type files

[suliveevil]

Is there a way to use CodeCompletion in undifined file type files?

This is TextMate:
You can define fileType

 1  {  scopeName = 'source.untitled';
 2     fileTypes = ( );
 3     foldingStartMarker = '\{\s*$';
 4     foldingStopMarker = '^\s*\}';
 5     patterns = (
 6        {  name = 'keyword.control.untitled';
 7           match = '\b(if|while|for|return)\b';
 8        },
 9        {  name = 'string.quoted.double.untitled';
10           begin = '"';
11           end = '"';
12           patterns = ( 
13              {  name = 'constant.character.escape.untitled';
14                 match = '\\.';
15              }
16           );
17        },
18     );
19  }

[blach]

Not really. You could possibly use "text.plain", since unknown file extensions use the "Plain Text" syntax definition by default.

[suliveevil]

Wow, trick get!
thank you very much!🥰🥰🥰