javascript转换陈述年龄范围[重复]

Question

这个问题已经在这里有了答案：

• 大于/小于 10个答案的 切换语句

卡在javascript开关分配上。 我对这些东西还很陌生，但是似乎无法在我的课程书或网上找到任何东西来使该程序正常工作。 任务是将if语句切换为代码。 任何帮助或建议，将不胜感激。

var myAge = prompt("Enter your age:", "30");

switch (myAge) {

  case myAge! >= 0:
  case myAge <= 10:
    document.write("myAge is NOT between 0 and 10 <br />");

  case myAge >= 0:
  case myAge <= 10:
    document.write("myAge is between 0 and 10 ");
    break;

  case myAge >= 80:
  case mmyAge <= 10:
    document.write("myAge is 80 or above or 10 or below ");
    break;

  case myAge >= 30:
  case myAge <= 39:
    document.write("myAge is between 30 and 39 ");
    break;

  case myAge >= 80:
  case myAge <= 89:
    document.write("myAge is between 80 and 89 ");
    break;
}

Answer 1

确保您使用的是int而不是字符串，以防万一：

var myAge = parseInt(prompt("Enter your age:", "30"));

并确保添加break; 对所有case的陈述。

删除! 第一种case字符： myAge! 到myAge

您得到什么确切的错误？

Answer 2

在第一个“ case myAge”中，比较运算符不起作用。 如果您试图说它不等于，则应输入！=，而不是！> =。

Answer 3

我以为那可以...

-------------------------旧答案

尝试以下； 顺便说一句你确定你需要document.write吗？

var myAge = ~~prompt("Enter your age:", "30"),
    msg = [];
switch (true) {

    case myAge < 0 && myAge > 10:
        msg.push("myAge is NOT between 0 and 10");

    case myAge >= 0 && myAge <= 10:
        msg.push("myAge is between 0 and 10");

    case myAge >= 80 || myAge <= 10:
        msg.push("myAge is 80 or above or 10 or below");

    case myAge >= 30 && myAge <= 39:
        msg.push("myAge is between 30 and 39");

    case myAge >= 80 && myAge <= 89:
        msg.push("myAge is between 80 and 89");
}
document.write(msg.join('<br />'));

---

但不是，原因如下：首先很明显，您想要获得更多验证消息； 不幸的是，这不能在单个开关中写入，导致运行了多个开关，您应该删除break; 但这意味着第一个满足条件的条件将导致所有后续条件都被执行...

说您必须移至一个“ multi-if”，看起来可能如下所示：

var myAge = parseInt(prompt("Enter your age:", "30"), 10),
    msg = [];

if (myAge < 0 && myAge > 10)
    msg.push("myAge is NOT between 0 and 10");
if (myAge >= 0 && myAge <= 10)
    msg.push("myAge is between 0 and 10");
if (myAge >= 80 || myAge <= 10)
    msg.push("myAge is 80 or above or 10 or below");
if (myAge >= 30 && myAge <= 39)
    msg.push("myAge is between 30 and 39");
if (myAge >= 80 && myAge <= 89)
    msg.push("myAge is between 80 and 89");

console.log(msg.join("\n"));

Answer 4

您错过了break和mmyAge 。 并通过true来switch 。

 var myAge = parseInt(prompt("Enter your age:", "30")); age(myAge); function age(myAge){ switch (true) { case (myAge >= 0 && myAge <=10): document.write("myAge is NOT between 0 and 10 <br />"); break; case myAge >= 0 && myAge <= 10: document.write("myAge is between 0 and 10 "); break; case myAge >=80 && myAge <=10: document.write("myAge is 80 or above or 10 or below "); break; case myAge >= 30 && myAge <=39: document.write("myAge is between 30 and 39 "); break; case myAge >= 80 && myAge <= 89: document.write("myAge is between 80 and 89 "); break; default: console.log(myAge); } }