How to use autocomplete/autocomplete correctly?

Question

JavaScript

Explain command autocompletion in editors.
I write in javascript. In sublimetext 3, command options do not appear at all, in the atom it works according to a principle I do not understand, it suggests something, but most people ignore it, in "visual studio code" it works as it should, but it considers any non-Javascript code in the file as an error and underlines it thick red line, as in the picture, maybe someone knows how to remove it.
In general, the ideal option is in Notepad ++, but for some reason he does not know all the commands, and I would like to change it already.
Either I don’t understand something how to set it up, or are these all normal options?
Also, I would use the atom or, as a last resort, visual studio code, if they helped me figure it out, I really liked them.

update
Perhaps I mixed up the terminology. I would like it to be like notepad++, not like atom.

Answer 1

Beginners should not use such tools, it is harmful.
At least six months of active work without auto-completions, otherwise it will take a long and painful time to finish your studies.