如何将空间保留在凯撒密码的输入字符串中？

Question

这个项目在JavaScript中。我需要确保输出保留输入到功能中的字符串中的空间。我要通过的测试是用13个字母的班次调用“ Hello World”一词的功能。从此代码中，结果是“ Uryyybjbeyq”和“ Uryyb jbeyq”。我已经确定我需要一个我已经包含的if语句，但不确定在继续关键字之前应包含什么命令，以插入所需的空间。我是初学者，这只是我的第三个项目，因此对任何帮助都将不胜感激。请在下面找到相应的代码。

function caesarCypher(string, num){
  // line below is the encrypted string we will return from the function
  const letters = 'abcdefghijklmnopqrstuvwxyz';
  
  let encryptStr = ""
  
  // loop through every character in the inputted string
  for(let i = 0; i < string.length; i++){
  // line below will look up index of char in alphabet  
    let char = string[i];
  /* if statement below is attempting to identify the space in the original string and then add a command that will add a space to the encrypted string then continue to work through the rest of the input */ 
    if (char === " ") {
  //need something to put on this line to insert space;
      continue;
    }

    let index = letters.indexOf(char);
  // index + num below will give us the letter 7 spots over 
    let newIndex = index + num;
  // if statement below makes the function loop back around 
    if (newIndex > 26) {
      newIndex = newIndex - 26;
    }
    
    let newChar = letters[newIndex];
    encryptStr += newChar;
        
  }
    
    return encryptStr;
  
}
/* invoke the function with these parameters to pass the test-- expected result is 'uryyb jbeyq'*/

caesarCypher("hello world", 13)

Answer 1

您可以添加这样的空白：

encryptStr += " ";

我尝试了您的代码，然后遇到了一个错误...所有字母都是一样的。这是我的做法：

function caesarCypher(string, num){
  let encryptStr = "";
  for(let i = 0; i < string.length; i++){
    let char = string[i];
    if (char === " ") {
        encryptStr += " "; //This adds a white space.
        continue;
    }
    // If you want to keep the case of a letter, skip the 
    // "toLowerCase()" and extend the condition below.
    let asciiCode = string.toLowerCase().charCodeAt(i) + num; 
    if(asciiCode > 122) {
        asciiCode -= 26;
    }
    encryptStr += String.fromCharCode(asciiCode);
  }
  return encryptStr;
}