Javascript switch语句不起作用--三个太多了吗？[副本]

Question

我是Javascript的新手，正在尝试通过制作一个小程序来学习，在这个程序中输入占星星座、行星和房屋来制作一个madlibs类型的小故事。为此，我在一个函数中放入了三个switch语句。

不确定这是不是太多的switch语句，但是，当我在Chrome上加载它时，有时我只得到text，有时我得到text和text2，有时我只得到text3。

有人知道为什么会这样吗？我只是在一个函数中有太多switch语句吗？我在网上搜索，但找不到一个函数中允许有多少个。

function tellMeaStory() {
  var text;
  var text2;
  var text3;
  var sign = document.getElementById("mySign").value;
  var planet = document.getElementById("myPlanet").value;
  var house = document.getElementById("myHouse").value;

  switch(sign) {
    case "Aries", "aries":
      text = "red";
      break;
    case "Taurus", "taurus":
      text = "calm";
      break;
    case "Gemini", "gemini":
      text = "quirky";
      break;
    case "Cancer", "cancer":
      text = "moody";
      break;
    case "Leo", "leo":
      text = "hungry";
      break;
    default:
      text = "sign";
  }

  switch(planet) {
    case "Sun", "sun":
      text2 = "hero";
      break;
    case "Moon", "moon":
      text2 = "mother";
      break;
    case "Mercury", "mercury":
      text2 = "twin";
      break;
    case "Venus", "venus":
      text2 = "courtesan";
      break;
    case "Mars", "mars":
      text2 = "soldier";
      break;
    default:
      text2 = "planet";
  }

  switch(house) {
    case "one", "One":
      text3 = "hole";
      break;
    case "two", "Two":
      text3 = "buffet";
      break;
    case "three", "Three":
      text3 = "database";
      break;
    case "four", "Four":
      text3 = "stomach";
      break;
    case "five", "Five":
      text3 = "wilderness";
      break;
    default:
      text3 = "house";
  }
  document.getElementById("demo").innerHTML += "You are a " + text + " " + text2 + " in a " + text3;
}

<input id="mySign" type="text" value="Enter your sign">
<input id="myPlanet" type="text" value="Enter your planet">
<input id="myHouse" type="text" value="Enter your house">

<button onclick="tellMeaStory()">Generate</button>
<div id="demo"></div>

Answer 1

您之所以看到奇怪的结果，是因为JavaScript处理逗号的方式。例如大小写“sun”，“sun”:不检查大小写是sun还是sun，它创建一个字符串“sun”与“sun”进行比较。对switch语句没有限制，但是对于“大多数”情况来说，它们并不是很好。如果你想重写这个来检查多个拼写，你可以用两种方法中的一种，至少我能想到。

反转您的switch语句

  switch(true) {
case (planet.toUpperCase() === "SUN"):
  text2 = "hero";
  break;
case (planet.toUpperCase() === "MOON"):
  text2 = "mother";
  break;
case (planet.toUpperCase() === "MERCURY"):
  text2 = "twin";
  break;
case (planet.toUpperCase() === "Venus"):
  text2 = "courtesan";
  break;
case (planet.toUpperCase() === "MARS"):
  text2 = "soldier";
  break;
default:
  text2 = "planet";
}

或者可以使用一个if语句链，一起跳过开关。

if(planet === "sun" || planet === "Sun" || planet === "SUn") {
  // text assignment
}

if (planet.toLowerCase() === "sun") { 
  // text assignment 
}