Question

我试图让我的头围绕js中的do / while循环和逻辑运算符。我的问题是将if / else if / else语句嵌入do部分时，因为它不断循环警报。此外，如果我输入除稀有，中等或完成之外的任何内容，它将进入else if语句而不是else语句，即使我已经为else if语句指定了中等或完成。我哪里错了？任何帮助将不胜感激。

感谢。

var food;
var steak;

food = prompt("Hey what type of food do you want to eat? We have steak,                  chicken, legumes, kangaroo or pufferfish?","Select your choice   here.").toUpperCase();

switch (food) {
    case 'STEAK':
        alert ("Sure no problem, how would you like your steak done?");
        steak = prompt("Would you like your steak done rare, medium or well-done?").toUpperCase();
            do {
                if (steak === "RARE") {
                    alert ("You eat the rare steak");
                }
                else if (steak === "MEDIUM"||"WELL-DONE") {
                    alert("You eat your steak and it's good.");
                }
                else {
                    alert("Sorry didn't catch that.");
                    steak = prompt("Choose rare, medium or well-done.");
                }
            } while (steak !== "RARE" || "MEDIUM" || "WELL-DONE");
        break;
}

Answer 1

你必须单独进行每次比较，所以

else if (steak === "MEDIUM"||"WELL-DONE") {
    alert("You eat your steak and it's good.");
}

应该是

else if (steak === "MEDIUM"|| steak === "WELL-DONE") {
    alert("You eat your steak and it's good.");
}

等等。这也是你无限的do / while循环的原因。

Answer 2

由于你在＆＃39;中的条件，它会进入无限循环。构造总是等于＆＃34; true＆＃34;。

您拥有的内容如下：

while (steak !== "RARE" || "MEDIUM" || "WELL-DONE")

将其更改为

while (steak !== "RARE" && steak !== "MEDIUM" && steak !== "WELL-DONE")

此外，您还有一个类似的问题，其他问题是＆＃39;声明。

else if (steak === "MEDIUM"||"WELL-DONE") {

将其更改为

else if (steak === "MEDIUM"|| steak === "WELL-DONE") {

您的脚本中仍然存在一些逻辑问题。请尝试以下内容：

var food;
var steak;

food = prompt("Hey what type of food do you want to eat? We have steak,                  chicken, legumes, kangaroo or pufferfish?","Select your choice   here.").toUpperCase();

switch (food) {
case 'STEAK':
    alert ("Sure no problem, how would you like your steak done?");

    steak = prompt("Would you like your steak done rare, medium or well-done?").toUpperCase();
    while (steak !== "RARE" && steak !== "MEDIUM" && steak !== "WELL-DONE") {
        alert("Sorry didn't catch that.");
        steak = prompt("Choose rare, medium or well-done.").toUpperCase();
    }

    if (steak === "RARE") {
        alert ("You eat the rare steak");
    }
    else if (steak === "MEDIUM"|| steak === "WELL-DONE") {
        alert("You eat your steak and it's good.");
    }            
    break;
}

如果它仍然无效，请告诉我。

Answer 3

如上所述，必须单独测试条件，即 if（a == n || a == m）

你最后的陈述也不正确。您可能想要执行类似

的操作

＆＃13;

var food;
var steak;

food = prompt("Hey what type of food do you want to eat? We have steak,                  chicken, legumes, kangaroo or pufferfish?","Select your choice   here.").toUpperCase();

switch (food) {
    case 'STEAK':
        alert ("Sure no problem, how would you like your steak done?");
        steak = prompt("Would you like your steak done rare, medium or well-done?").toUpperCase();
        console.log('steak', steak);
            do {
                console.log('steak inside do', steak);
                if (steak === "RARE") {
                    alert ("You eat the rare steak");
                }
                else if (steak === "MEDIUM"|| steak ==="WELL-DONE") {
                    alert("You eat your steak and it's good.");
                }
                else {
                    alert("Sorry didn't catch that.");
                    steak = prompt("Choose rare, medium or well-done.").toUpperCase();
                }
            } while (steak !== "RARE" && steak !== "MEDIUM" && steak !== "WELL-DONE");
        break;
}

＆＃13;

为我工作。

do / if语句中的if elseif语句无限循环javascript

3 个答案: