setSelection method logic

[DmitryKa]

Hi guys.

Could you explain me the logic of the setSelection methods for my case?

E.g. I have a pattern (111) 111-1111. I want to edit number starting from the fourth digit.

So, I call setSelection({start: 6, end: 6}), but... Oh! That sets selection to {start: 4, end: 4}! Ok, I think, it's okay if it works correctly. But.. when I try to paste some digits it just skips first of them and only after this skipping selection becomes {start: 6, end: 6}. Of course, other numbers paste normally after that.

So, tell me pls what's the logic of this work and if there are mistakes how should it work?