Javascript: Janken Function

Java, Script, Function, Janken

let userChoice = prompt(
        "Do you choose rock, paper or scissors?"
    ),
    computerChoice = Math.random();
computerChoice = computerChoice <= .34 ?
    "rock" : computerChoice <= .67 ?
    "paper" : "scissors", alert(
        "Computer: " + computerChoice
    );
const compare = function(o, r) {
    return o === r ?
        "The result is a tie!" :
        "rock" === o ?
        "scissors" === r ?
        "rock wins" : "paper wins" :
        "paper" === o ? "rock" ===
        r ? "paper wins" :
        "scissors wins" :
        "scissors" === o ?
        "rock" === r ? "rock wins" :
        "scissors wins" : void 0
};
alert(
    compare(userChoice, computerChoice)
    );