Cheikhou Kouyate put visiting West Ham in the lead midway through the first half, and Diafra Sakho doubled the advantage just past the hour mark.
Tottenham have proven time and time again this season that they can stage late comebacks, and they did so on Sunday.
Danny Rose halved the deficit in the 81st minute with a long-range effort, and England Under-21 international striker Harry Kane equalised in the sixth minute of injury time.
Jenkinson, who is currently on loan at West Ham from Arsenal, has now spoken of his surprise at the final result.
"I couldn't see us conceding another goal,” the 23-year-old right-back told West Ham’s official website. “I thought we were comfortable at 2-1 and they didn't really look like scoring.
"Obviously they've equalised with the last kick of the game, it's unbelievable really. That's the way it goes sometimes but it was very unfortunate.”
This was not the first time that Tottenham had come from behind to rescue a point with a late goal, and one suspects that the West Ham players should have realised that Mauricio Pochettino's players do not give up until the final second.
Playing at home gave the Spurs players an added impetus, and West Ham should not have “thought” for a second that they were “comfortable” when they were 2-1 up.