Question

简单的问题..不确定为什么会发生这种情况......

问题：即使 if 语句为true，“ else ”也会运行。

在这种情况下......

进入的城市是“Los Angelos”，这是var“theAnswers”的数组元素意味着警报应该运行，程序应该完成......

反而会发生什么......

程序显示else警报..然后显示正确的警报（如果）。亲眼看看......

var theAnswers = ["New York City", "Chicago", "Los Angelos", "Cleveland", "Ohio", "Seattle", "Boston", "Miami", "Philadelphia"];

var userAnswer = prompt("I am thinking of a Major City.. guess which one it is?", "Los Angelos");
userAnswer = userAnswer.toLowerCase();

for (var i = 0; i < theAnswers.length; i++) {
    if (userAnswer === theAnswers[i].toLowerCase()) {
        alert("Good, your guess is correct. You get one point!");
        break;
    }

    else{
        alert("Hmm... not quite the City I was looking for... Better luck next time!");

    }
}

Answer 1

那是因为您在else中为您所做的每项检查都显示了该消息。它将显示每个城市不匹配的消息。首先查看所有城市，然后显示一次结果：

var found = false;
for (var i = 0; i < theAnswers.length; i++) {
    if (userAnswer === theAnswers[i].toLowerCase()) {
        found = true;
        break;
    }
}
if (found) {
    alert("Good, your guess is correct. You get one point!");
}else{
    alert("Hmm... not quite the City I was looking for... Better luck next time!");
}

Answer 2

删除for循环。您不必循环遍历数组以了解其中是否存在答案，只需知道它的位置就足够了。试试这个：

var theAnswers = ["New York City", "Chicago", "Los Angelos", "Cleveland", "Ohio", "Seattle", "Boston", "Miami", "Philadelphia"];
var userAnswer = prompt("I am thinking of a Major City.. guess which one it is?", "Los Angelos");

if (theAnswers.indexOf(userAnswer)>=0) {
    alert("Good, your guess is correct. You get one point!");
}else{
    alert("Hmm... not quite the City I was looking for... Better luck next time!");
}

Fiddle

Answer 3

它实际上并没有执行＆＃34; else＆＃34;当条件成立时。

if (userAnswer === theAnswers[i].toLowerCase())

第一次评估这个条件时，我是0，所以答案[i]是＆＃34;纽约市＆＃34;。

即使“if”语句为真，循环遍历Array也会执行“else”（Javascript）

3 个答案: