Question

这个提示工作非常顺利，直到我更新了其他一些javascript。我不知道我是怎么搞砸的。此函数在body标记中声明为运行＆＃39; onload＆＃39;。

function funcPrompt() {
   var answer = prompt("Are you a photographer?", "Yes/No");
   answer = answer.toLowerCase();

if (answer == "yes") {
    alert('Excellent! See our links above and below to see more work and find contact info!');
}
else if(answer == "no") {
    alert('That is okay! See our links above and below to learn more!');
}
else if(answer == null || answer == "") {
    alert('Please enter an answer.');
    funcPrompt();
}
else {
    alert('Sorry, that answer is not an option');
    funcPrompt();
}
}

现在我突然收到此错误并且提示不会出现。

Answer 1

如果我们点击取消，提示将返回null，并且无法在toLowerCase上应用null（会导致异常！）

在所有其他条件之前添加条件answer===null，并return停止执行function

＆＃13;

function funcPrompt() {
  var answer = prompt("Are you a photographer?", "Yes/No");
  if (answer === null || answer === "") {
    alert('Please enter an answer.');
    funcPrompt();
    return;
  }
  answer = answer.toLowerCase();
  if (answer == "yes") {
    alert('Excellent! See our links above and below to see more work and find contact info!');
  } else if (answer == "no") {
    alert('That is okay! See our links above and below to learn more!');
  } else {
    alert('Sorry, that answer is not an option');
    funcPrompt();
  }
}
funcPrompt();

＆＃13;

Answer 2

不确定为什么会得到null，但是如果要避免使用null，请使用以下方法：

app.use(bodyParser.json()) // for parsing application/json app.use(bodyParser.urlencoded({ extended: true }))

Answer 3

在您的情况下，最好使用确认而不是提示

＆＃13;

function funcConfirm() {
  var answer = confirm("Are you a photographer?");

  if (answer === true) {
    alert('Excellent! See our links above and below to see more work and find contact info!');
  } else {
    alert('That is okay! See our links above and below to learn more!');
  }
}

funcConfirm();

＆＃13;

未捕获的TypeError：无法读取属性＆＃39; toLowerCase＆＃39;为null

3 个答案: