Question

我被困在JavaScript实验室的一部分，我需要：

提示用户输入
然后使用switch语句根据输入的内容显示警告
然后检查其文字而不是数字

我的老师说要把它放在一个循环中，到目前为止我已经使用了所有这些问题，但我只是让自己更加困惑。

这是我的代码：

<script>
        //array to compare input to
        var days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

        do
        {
            //prompt user for input
            var response = prompt("Choose a day of the week: ");

                //loop through all array elements
                for(i in days)
                {
                        //choices that I will use to compare input to
                        switch(response)
                            {
                                case days[0]:
                                case days[1]:
                                case days[2]:
                                case days[3]:
                                case days[4]:
                                case days[5]:
                                case days[6]:
                                    alert("You have chosen day: " + days[i]);
                                    break;
                                default:
                                    alert("That is not a choice!");
                            }
                    }
            }//condition while input doesn't equal exactly array element prompt user again
        while(response !=== days[i]);
    </script>

Answer 1

var days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

    do
    {
        //prompt user for input
        var response = prompt("Choose a day of the week: ");

            //loop through all array elements

                    //choices that I will use to compare input to
                    switch(response)
                        {
                            case days[0]:
                            case days[1]:
                            case days[2]:
                            case days[3]:
                            case days[4]:
                            case days[5]:
                            case days[6]:
                                alert("You have chosen day: " + days[days.indexOf(response)]);
                                break;
                            default:
                                alert("That is not a choice!");
                        }

        }//condition while input doesn't equal exactly array element prompt user again
    while(response !== days[i]);

有两处更正

一个不需要for循环，使用

的indexOf

以天为单位获取输入日索引的方法

第二个是关系运算符的错误使用！===应该是！==。

Answer 2

您最好删除for-in循环。现在你有2个循环do-while，只需要一个循环。将数组与响应进行比较的更好方法是使用indexOf并在匹配时中断循环。

＆＃13;

//array to compare input to
var days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

do {
  //prompt user for input
  var response = prompt("Choose a day of the week: ");

  //loop through all array elements
  //choices that I will use to compare input to
  switch (response) {
    case days[0]:
    case days[1]:
    case days[2]:
    case days[3]:
    case days[4]:
    case days[5]:
    case days[6]:
      alert("You have chosen day: " + response);
      break;
    default:
      alert("That is not a choice!");
  }
} //condition while input doesn't equal exactly array element prompt user again
while (days.indexOf(response) === -1);

＆＃13;

这是一个品味问题，但您也可以通过删除switch语句并在while循环中运行它来清理它：

＆＃13;

var days = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];

while(true) {
  var response = prompt("Choose a day of the week: ");
  
  var found = days.find(function(day) {
    return response === day;
  });

  if (found) {
    alert("You have chosen day: " + response);
    
    break;
  }

  alert("That is not a choice!"); 
}

＆＃13;

Answer 3

@alejandro-martin的好玩法....

＆＃13;

import * as functions from 'firebase-functions';
import * as express from 'express';

const app = express();

app.get("/:function", (req, res) => {
    switch(req.params.function) {

        case 
            "helloWorld" : helloWorld(res)
            break;

        default : res.send("Invalid function requested.")

    }
});

app.get("/users/:id", (req, res) => {
    res.send("User with ID: " + req.params.id)
});

function helloWorld(res) {
    res.send("Hello world!");
}

exports.api = functions.https.onRequest(app);

＆＃13;

Answer 4

var daysList = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'];
isResponseValid = false;

do {
  var response = prompt('Choose a day of the week');
  if ( /^[0-9]*$/.test(response) ) {
    alert('You have key in a number, please key in a text');
  }
  else if( daysList.indexOf(response) >= 0){
    alert('You have chosen ' + response);
    isResponseValid = true;
  } else {
    alert('That is not a choice');
  }
} while (isResponseValid == false);

if语句的第一行是测试文本。在验证响应不是数组的一部分后，测试数字没有意义。

流程应为：

测试号码，如果是号码，则提醒用户他们必须键入文本。
如果是文本，请测试文本是否在数组中。
如果测试失败，请提醒用户输入不是一个选择。

这里没有使用开关盒，因为它对我来说似乎没什么意义。但上面的答案提供了如何在代码中使用它们的示例。

添加了一个额外的var来测试响应是否有效，但我想使用响应没有额外的好处！== days [i]。 :)

提示用户输入然后使用开关检查输入

4 个答案: