Basic JavaScript RPS Game

function rps() {
    var playornah = confirm('Do you want to play Rock Paper Scissors?')
    if (playornah == true) {
        playRPS();
    }

    function playRPS() {
        var userChoice = prompt('Choose Rock, Paper, or Scissors!\n\n \(All lowercase.\)')
        switch (Math.round(Math.random() * (3- 1) + 1)) {
            case 1:
                compChoice = "rock";
                break;
            case 2:
                compChoice = "paper";
                break;
            case 3:
                compChoice = "scissors";
                break;
        }
        if (compChoice == "rock" && userChoice == "rock") {
            playagain = confirm('It was a tie!\nBoth opponents chose Rock!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "paper" && userChoice == "paper") {
            playagain = confirm('It was a tie!\nBoth opponents chose Paper!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "scissors" && userChoice == "scissors") {
            playagain = confirm('It was a tie!\nBoth opponents chose Scissors!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "rock" && userChoice == "scissors") {
            playagain = confirm('You lost!\nThe opponent chose Rock, while you chose Scissors!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "rock" && userChoice == "paper") {
            playagain = confirm('You won!\nThe opponent chose Rock, while you chose Paper!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "paper" && userChoice == "rock") {
            playagain = confirm('You lost!\nThe opponent chose Paper, while you chose Rock!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "paper" && userChoice == "scissors") {
            playagain = confirm('You won!\nThe opponent chose Paper, while you chose Scissors!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "scissors" && userChoice == "rock") {
            playagain = confirm('You won!\nThe opponent chose Scissors, while you chose Rock!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (compChoice == "scissors" && userChoice == "paper") {
            playagain = confirm('You lost!\nThe opponent chose Scissors, while you chose Paper!\n\nPlay again?')
            if (playagain == true) {
                playRPS();
            } else {
                alert('Closing Game.')
            }
        } else if (userChoice == null) {
            alert('Closing Game.')
        } else {
            alert('Invalid Input.\nPlease type all inputs in lowercase with correct spelling.')
            playRPS();
        }
    }
}
rps();