Actually, there's no ending in the game, but it does reset itself to zero after the player reached the highest possible score (99,999). T-Rex Dino is an endless runner game. If you're wondering whether there are more levels, or a final level, or someone to fight nope, there's none of that.
Otherwise, if you have an internet connection, type in chrome://dino into a new tab. Internet or no internet, you should see a black and white dinosaur and Press space to play. Once you press the Space bar, the game starts. Keep pressing space to avoid hitting birds and cacti.