Question

我的if-else代码块运行良好，除了最后一个使用AND逻辑运算符的条件。我是JavaScript的新手，我无法弄清楚哪里出了问题！想法？

我尝试添加方括号，删除方括号并重新调整语句。

//declare variables the prompts the user to state their birthdate in 
//month, day and year
var birthYear = prompt('What year were you born in?');
var birthMonth = prompt('What month were you born in? In numerals please!');
var birthDay = prompt('What day of the month were you born on? In numerals please!');

//declare variables to get current date
var now = new Date();
var currentYear = now.getFullYear();
var currentMonth = now.getMonth() + 1; //so now January = 1
var currentDay = now.getDate();
//declare variable for age will turn this year
var age = currentYear - birthYear;
//declare variable for text output
var text = "";
//create if/else loop for three different scenarios
if (birthMonth < currentMonth) {
  text += "You have turned " + age + " years old already this year.";
} else if (birthMonth > currentMonth) {
  text += "You will be turning " + age + " years old later this year.";
} else if (birthMonth === currentMonth && birthDay === currentDay) {
  text += "Today is your Birthday! Happy Birthday!";
}

document.getElementById('agestate').innerHTML = text;

<p id="agestate"></p>

当提示您返回“今天是您的生日。生日快乐！”的提示时，我应该能够输入当前的月份和日期。

Answer 1

请勿使用严格等于（===）。标准==应该在这里起作用，因为您的数据类型不兼容：birthMonth是字符串，而currentMonth是整数，因此严格相等将失败。另外，您可以在比较之前将字符串转换为数字（反之亦然）。

您可以尝试以下最新更新的代码（在提示中输入今天的日期以显示“今天是您的生日！”

//declare variables the prompts the user to state their birthdate in 
//month, day and year
var birthYear = prompt('What year were you born in?');
var birthMonth = prompt('What month were you born in? In numerals please!');
var birthDay = prompt('What day of the month were you born on? In numerals please!');

//declare variables to get current date
var now = new Date();
var currentYear = now.getFullYear();
var currentMonth = now.getMonth() + 1; //so now January = 1
var currentDay = now.getDate();
//declare variable for age will turn this year
var age = currentYear - birthYear;
//declare variable for text output
var text = "";

//create if/else loop for three different scenarios
if (birthMonth < currentMonth) {
    text += "You have turned " + age + " years old already this year.";
} else if (birthMonth > currentMonth) {
    text += "You will be turning " + age + " years old later this year.";
} else if (birthMonth == currentMonth && birthDay == currentDay) {
    text += "Today is your Birthday! Happy Birthday!";
}

console.log(text);

Answer 2

在FrankerZ答案的基础上，request.session函数返回的是字符串而不是数字，但是我不鼓励使用prompt，因为它是javascript严重的随机行为之一，在任何其他情况下（理智）试图比较字符串和数字的语言不会编译或引发错误，但是javascript具有隐藏的行为，具有松散的相等性，您可以详细了解here

我建议您改用数字分析和==（也可以处理缺少的大小写）：

===

我缺少什么，以便我的Logic运算符可以对if-else语句正常工作？

2 个答案: