A rather annoying feature of vim is that if you are in insert mode and do an autocomplete (Ctrl-N), arrow key down to the desired item, and press the Enter key, then it inserts the item but also inserts a newline which you then have to delete.
Is there a way to select an item out of the autocomplete list without getting an additional unwanted newline?
Best Answer
It depends on which popup menu state you are in (see
:help popupmenu-completion). I understand from your question that you're in state 2 (since you've pressed arrow keys to find a completion). However, the default behavior for Enter in state 2 is to insert the completion without newline; what you describe is normally the behavior of state 1 (which is when you use Ctrl+N/Ctrl+P.)A way that works consistently in all states is to use Ctrl+Y. I like to remember the Y as standing for "yes, accept that word." It's also possible to just start typing the text that should come after the completed word, unless you've remapped things as in geedoubleya's answer.
In the same context, you can press Ctrl+E to cancel the menu and leave your text as it was before you invoked it. If you're used to the pairings of Ctrl+E and Ctrl+Y in other contexts (e.g. to scroll up or down in normal mode, or to insert the character below or above the cursor in insert mode), that's one way to remember it here. I guess you could also think of it as "exiting" the menu or similar.
See
:help popupmenu-keysfor more.