Question

我正在尝试并且未能使用javascript检查5位整数是否是回文。我已经得到了正确检查5位数字符串的代码（还没有整数）。那部分应该比较容易弄明白。

我的主要问题：我在javascript中使用函数的结构吗？如果是这样，我怎样才能使函数调用正常工作？它只是在收到所需的输入后退出程序。

代码如下：

    <script type="text/javascript"> 
                    var userInput;
                    var counter = 0;

                    function palindrome(userInput) {
                        var re = /[^A-Za-z0-9]/g;

                        userInput = userInput.toLowerCase().replace(re, '');
                        var len = userInput.length;

                        for (var i = 0; i < len/2; i++) {
                            if (userInput[i] !== userInput[len - 1 - i]) {
                            return false;
                            }
                        }
                        return true;
                    }

                    userInput = window.prompt("Please enter a 5-digit, numerical palindrome: ");
                    palindrome(userInput);

                    while (counter < 10){
                        if (userInput.length == 5){
                            if (pandindrome(userInput) == true){
                                document.write("The input is a palindrome!");
                            }
                            else if (pandindrome(userInput) == false){
                                document.write("The input is not a palindrome! Try again!");

                                userInput = window.prompt("Please enter a 5-digit, numerical palindrome: ");
                                palindrome(userInput);
                            }   
                        counter++;
                        }
                        else if (userInput.length != 5){
                            alert("The input you entered was not 5-digits! Please try again!");

                            userInput = window.prompt("Please enter a 5-digit, numerical palindrome: ");
                            palindrome(userInput);
                        }
                    }
                </script>

Answer 1

我已经测试了你的代码，一切正常！

FIY，我设置一个变量isPalindrome来存储函数回文的返回值。然后你可以直接在if语句中使用它，而不是比较为true。

var userInput;
var counter = 0;

function palindrome(userInput) {
  var re = /[^A-Za-z0-9]/g;

  userInput = userInput.toLowerCase().replace(re, "");
  var len = userInput.length;

  for (var i = 0; i < len / 2; i++) {
    if (userInput[i] !== userInput[len - 1 - i]) {
      return false;
    }
  }
  return true;
}

userInput = window.prompt("Please enter a 5-digit, numerical palindrome: ");
var isPalindrome = palindrome(userInput);

while (counter < 10) {
  if (userInput.length == 5) {
    if (isPalindrome) {
      document.write("The input is a palindrome!");
    } else {
      document.write("The input is not a palindrome! Try again!");

      userInput = window.prompt(
        "Please enter a 5-digit, numerical palindrome: "
      );
      isPalindrome = palindrome(userInput);
    }
    counter++;
  } else if (userInput.length != 5) {
    alert("The input you entered was not 5-digits! Please try again!");

    userInput = window.prompt("Please enter a 5-digit, numerical palindrome: ");
    isPalindrome = palindrome(userInput);
  }
}

使用javascript检查整数回文

1 个答案: