当输入不是月份时循环提示

Question

我试图在用户输入错误时循环提示。我在谷歌上搜索并点击了几乎所有的顶部链接，尝试了 while 循环和 for 循环，但没有任何进展。当我使用我发现的循环方法时，我的按钮不再可单击或单击但当我输入无效月份时，没有显示任何警报，并且它不会循环。如果有人能指出我正确的方向，或者告诉我我做错了什么，我将不胜感激！！

function myFunction() {
  
  

  let text;
  let month = prompt("What month would you like to know about?","Please type your answer here").toLowerCase();
  
  switch(month) {
    case "january":
      text = "There are 31 days in the month of January";
      break;
    case "february":
      text = "There are 28 days in the month of february, and 29 days on a leap year!";
      break;
    case "march":
      text = "There are 31 days in the month of March";
      break;
    case "april":
      text = "There are 30 days in the month of April";
      break;
    case "may":
      text = "There are 31 days in the month of May";
      break;
    case "june":
      text = "There are 30 days in the month of June";
      break;
    case "july":
      text = "There are 31 days in the month of July";
      break;
    case "august":
      text = "There are 31 days in the month of August";
      break;
    case "september":
      text = "There are 30 days in the month of September";
      break;
    case "october":
      text = "There are 31 days in the month of October";
      break;
    case "november":
      text = "There are 30 days in the month of November";
      break;
    case "december":
        text = "There are 31 days in the month of December";
      break;

  }
  document.getElementById("days").innerHTML = text;

}

Answer 1

在switch语句中，可以设置一个default条件，当none个case满足条件时执行。在您的情况下，您只需在默认情况下调用 myFunction 即可“循环”。

当然这不会在用户提供有效月份时再次要求提示。

function myFunction() {
  let text = null;
  let month = prompt("What month would you like to know about?", "Please type your answer here").toLowerCase();

  switch (month) {
    case "january":
      text = "There are 31 days in the month of January";
      break;
      // fill all your cases
    default:
      text = "Incorrect input";
      alert('Incorrect input, attempting prompt again');
      myFunction();

  }
  if (text)
    document.getElementById("days").innerHTML = text;

  // myFunction(); uncomment this if you want the loop to go on even when the user provides a valid month as input

}

Answer 2

你可以试试这个

const regularMonthConfig = {
  january: 31,
  march: 31,
  april: 30,
  may: 31,
  june: 30,
  july: 31,
  august: 31,
  september: 30,
  october: 31,
  november: 30,
  december: 31
}

const february = 'There are 28 days in the month of february, and 29 days on a leap year!'

const otherMonths = Object.fromEntries(Object.entries(regularMonthConfig).map(([month, days]) => [month, `There are ${days} days in the month of ${month}`]))

const configMonths = {
  february,
  ...otherMonths
}
const ask = () => {
  let month = prompt("What month would you like to know about?", "Please type your answer here").toLowerCase();

const response = configMonths[month.toLowerCase()]|| "invalid month retry" 

document.getElementById("days").innerHTML = response;
}

ask()

<div id="days"></div>

当输入不是月份时循环提示

Loop prompt when input isn't a month

javascript

loops

prompt

switch-statement