Javascript-代码中输入错误的意外结束

我无法使此代码正常工作。它总是说输入意外结束，我不知道如何解决它。请帮忙。我的代码看起来与codecademys剪刀石头纸js代码中的代码相似，因为它与我试图自定义和修改的代码相同，但我无法使它正常工作

var myFunction = function () {
        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);

        var compare = function (userChoice, computerChoice) {

            if (userChoice === computerChoice) {
                console.log("The result is a tie!")
            } else if (userChoice === "rock") {
                if (computerChoice === scissors) {
                    console.log("rock wins")
                } else {
                    console.log("paper wins")
                }
            } else if (userChoice === "paper") {
                if (computerChoice === "rock") {
                    console.log("paper wins")
                } else {
                    console.log("scissors wins")
                }
            }
        }