JS: Rock, Paper, Scissors

gistfile1

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";
}

function compare (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 {
            return('scissors wins');
        }
    } else if (choice1 === 'scissors') {
        if (choice2 === 'paper') {
            return('scissors wins');
        } else {
            return('rock wins');
        }
    }
}

compare(userChoice, computerChoice);