Does the chess.com engine check for checkmate at every move?

Thanks. If you know Javascript you can check the source code with Google´s inspection tool I think. I dont know Javscript because I dont like people making fun of me.

This thread has been hard for me to understand from the beginning, or I am missing something.  The chess engine is presumed to obey the rules of chess.  Asking whether it will time you out even if you checkmate before the clock reaches zero, is no different than asking if it will let you move a rook diagonally.  If it programmed correctly, and there is no reason to think it isn't, then it will do the correct thing in all situations.  

Definitely, I will try it! By the way a humble advice: don't care what others think, just do what you love. Thanks!

You are missing something. 

Turtles dont have feelings, its all show.

Checkmate on the board takes precedence over the clock.

BUT

Here, there have been a few glitches where checkmate will  occasionally appear on the player's board but they still lose on time. This is explained by there being lag in the system. The move wasn't made in time, but it shows up as having been made due to the home computer lagging behind the server. If you go back through the game analysis, you will see the clock reading 0:00 and the move isn't registered. 

Computers work really fast these days; checking for checkmate is simple for them to do, even on a lowend smart phone w/ a tiny 1.2GHz ARM processor that still have to handle telephone functions.  You won't feel it.  I've written many chess programs, some even for the phone, which I try to cut down on processing power to save battery.  Checking for checkmate uses very little computing power.

I suspect this have to do with the chess.com programming of the remote clock.  t isn't too far fetched to assume the following sequence:

1. you checkmate your opponent on your PC

2. your PC, the program confirms checkmate and tells you

3. your PC sends movement update to chess.com server

4. chess.com server sends time expired message to your PC

(3 and 4 can reverse and you still get the same result)

For all intents and purposes, the computer's confirmation that a move is checkmate is as instantaneous as checking to see if a move is legal.

In programming complexity they are the same: O(1).  However, checkmate check does carry slightly more computations (e.g. if you move a piece, you only have to check for king safety, checkmate checks for king's escape routes' safeties as well).  But, as far as our human reaction time, it is , as you say, instantaneous.

Agreed, which is why I answered the way I did in post #26.