why undefined is not literals?

hi im peter cho from south korea.
and front end senior developer.

i have some question about undefined and null.

undefined is defined in global object since es3.
null and undefined are similar. so, i think undefined can be literals.

why undefined is defined in global object?
why undefined is not defined in literals?

please let me know (_ _)

If you mean that undefined is not a keyword, and null is - I'm not sure why this was originally the case, but changing it now (or likely even back in ES3) would break the web.