Game: Rock, Paper, Scissors

var userChoice = prompt("Do you choose rock, paper or scissors?");
var computerChoice = Math.random();
if (computerChoice < 0.34) {
    computerChoice = "rock";
} else if(computerChoice <= 0.67) {
    computerChoice = "paper";
} else {
    computerChoice = "scissors";
} console.log("Computer: " + computerChoice);

console.log("Your choice: " + userChoice);
choice1 = userChoice;
choice2 = computerChoice;

var compare = function(choice1, choice2) {
    if (choice1 === choice2) {
        return "The result is a tie!";
    } else if (choice1 === "rock") {
        if (choice2 === "scissors") {
            return "rock wins";
        }
        else {
            return "paper wins";
        }
    } else if (choice1 === "paper") {
        if (choice2 === "rock") {
            return "paper wins"
        }
        else if (choice2 === "scissors") {
            return "scissors win"
        }
        else {
            return "The result is a tie!"
        }
    } else if (choice1 === "scissors") {
        if (choice2 === "paper") {
            return "scissors win"
        }
        else {
            return "rock wins"
        }
    } else if (choice1 != "rock" || "paper" || "scissors") {
        return "Invalid input, please try again later."
    }
}
confirm("Your choice: " + userChoice + ". " + "Computer: " + computerChoice + ".  " + compare(choice1,choice2))