类型错误toLowercase不是一个函数

Question

我开始学习javascript。我有一个任务，我必须在计算机上创建一个简单的摇滚，剪刀游戏。

该程序最终会促使人类在转弯时输入摇滚，纸张或剪刀。为了确保数据验证，程序必须对人类输入的任何字母进行资本化。

为此，我尝试使用toLowercase函数，可以在下面的第二行代码中看到。

作为回报，我在控制台中收到以下内容：

TypeError：playerSelection.toLowercase不是函数

function playRound(playerSelection, computerSelection) {


    playerSelection = playerSelection.toLowercase();
    var resultMessage = "";

    if (playerSelection == "rock" && computerSelection == "paper") {
        resultMessage = "You Lose. Paper beats Rock"; 
    }

    else if (playerSelection == "rock" && computerSelection == "scissors") {
        resultMessage = "You Win. Rock beats Scissors"; 
    }

    else if (playerSelection == "paper" && computerSelection == "scissors") {
        resultMessage = "You Lose. Scissors beats Paper"; 
    }

    else if (playerSelection == "paper" && computerSelection == "rock") {
        resultMessage = "You Win. Paper beats Rock"; 
    }

    else if (playerSelection == "scissors" && computerSelection == "paper") {
        resultMessage = "You Win. Scissors beats Paper"; 
    }

    else if (playerSelection == "scissors" && computerSelection == "rock") {
        resultMessage = "You Win. Scissors beats Rock"; 
    }

    else {
        resultMessage = "Draw";
    }

    return resultMessage;

}

console.log(playRound("rock",compPlay));

Answer 1

不是，toLowerCase()是。 （不是案例，更多是Camel case）。