Currently your picks for computerChoice are a bit unfair:
14% chance to get rock
37-14=23 % chance to get paper
53-37 =16% chance to get scissors
75-53 = 22% chance to get lizard
100-75 = 25% chance to get spock
Why not make it easier and use <= 1/5, <=2/5 aso so you're save that all have equal chance and do not even need to bother about the exact numbers.
And for the tie case:
var newUserChoice = prompt("Please try again!");
choice1 = newUserChoice;
This lets the user pick again and returns the new choice which might be pretty strange:
User: Tell me who wins: "Rock vs Rock"
Almighty compare function: Spock
I would recommend that you just stick with the tie message and in the end get the result of
and use this to determine your next steps:
- let player and user choose again and run compare a second time