Javascript 简单开关语句

我试图用javascript编写一个简单的switch语句，询问用户的输入速度。令我沮丧的是，当这段代码执行最后一个警报时，我得到的总是默认情况。请告诉我我做错了什么

根据我的经验，开关箱中不能有操作员；你必须有一个确定的值。在这种情况下，即使开关看起来更好，也应该使用IF-ELSE块

---

编辑：我还找到了一个类似问题的答案。

在比较提示响应之前，需要将其转换为整数，并且需要将开关更改为一组IFs

var speed = prompt("Do you know how to type?");
speed = speed.toLowerCase();
if (speed === "yes" ) {
    var howFast = prompt("what is your wpm?(the answer must be a number between 1 and 200");
    switch(howFast) {
        case (howFast <= 10):
        console.log("you are a snail! practice and type at least 20 wpm, then try this again.");
        break;
        case (howFast <= 30):
        console.log("you are still pretty slow, but you're getting there!");
        break;
        case (howFast <= 50):
        console.log("you are getting there, keep trying");
        break;
        case (howFast <= 90):
        console.log("WoW! Excellent job! Your tenacity has paid off");
        break;
        case (howFast > 90):
        console.log("you are a megaracer! congratulations!");
        break;
        default:
        console.log("DOES NOT COMPUTE... You're either superfast or playing around!");



        }

    } else { alert("learn how to type and comeback.");}

只要改变一下：

<script>
    var speed = prompt("Do you know how to type?");
    var howFast;
    var logMessage;

    speed = speed.toLowerCase();

    if (speed === "yes" ) {
        howFast = parseInt(prompt("what is your wpm?..."));
        logMessage = "DOES NOT COMPUTE... You're either superfast or playing around!";

        if (howFast <= 10)
            logMessage = "you are a snail! practice and type at least 20 wpm, then try this again.";

        if (howFast <= 30)
            logMessage = "you are still pretty slow, but you're getting there!";

        if (howFast <= 50)
            logMessage = "you are getting there, keep trying";

        if (howFast <= 90)
            logMessage = "WoW! Excellent job! Your tenacity has paid off";

        if (howFast > 90)
            logMessage = "you are a megaracer! congratulations!";

        console.log(logMessage);

    } else {

        alert("learn how to type and comeback.");

    }
</script>

到

它应该会起作用。

---

演示：：

这有点像黑客，但您可以在JS case语句中使用如下表达式：

switch(true) {
..

我让这个工作：

var wpm = parseInt(howFast); // convert string to number first

switch(true)
{
    case wpm >= 0 && wpm <= 10:
    console.log('snail');
    break;

    case wpm > 10 && wpm <= 30:
    console.log('slowpoke');
    break;

    // etc.
}

jsFiddle：

---

希望对您有所帮助

在这种情况下，没有适用于每种情况的表达式，因此，使用if-else块代替switch更有意义。

尝试switchparseInthowFast

var wpm = parseInt(howFast); // convert string to number first

switch(true)
{
    case wpm >= 0 && wpm <= 10:
    console.log('snail');
    break;

    case wpm > 10 && wpm <= 30:
    console.log('slowpoke');
    break;

    // etc.
}

var speed = prompt("Do you know how to type?");
speed = speed.toLowerCase();
if (speed === "yes" ) {
    var howFast = prompt("what is your wpm?(the answer must be a number between 1 and 200");
    switch(true) {
        case (parseInt(howFast) <= 10):
        console.log("you are a snail! practice and type at least 20 wpm, then try this again.");
        break;
        case (parseInt(howFast) <= 30):
        console.log("you are still pretty slow, but you're getting there!");
        break;
        case (parseInt(howFast) <= 50):
        console.log("you are getting there, keep trying");
        break;
        case (parseInt(howFast) <= 90):
        console.log("WoW! Excellent job! Your tenacity has paid off");
        break;
        case (parseInt(howFast) > 90):
        console.log("you are a megaracer! congratulations!");
        break;
        default:
            console.log("DOES NOT COMPUTE... You're either superfast or playing around!");  
    }
    } else { alert("learn how to type and comeback.");}