当月份不在1-12之间时抛出一个错误

Question

因此，我试图用以下代码验证bith的日期，但我在实现if语句时遇到了问题，该语句检查month是否大于12，它应该抛出一个错误，如果day大于31，它也应该这样做。我非常感谢你的帮助。

function isYearCorrect(string) {
let dateOfBirth = new Date((string.substring(0, 2)), (string.substring(2, 4) - 1), (string.substring(4, 6)))
let year = dateOfBirth.getFullYear();
let month = dateOfBirth.getMonth() + 1;
let day = dateOfBirth.getDate();
let isDOBValid = false;
if (month < 10) {
month = "0" + month;
}
/**This statement does not check to see if the month ranges from 1 - 12 but it skips
to the next year and month and leaves the day as is. Basically 971315 becomes 1998-01-15*/
if (month > 12) {
return (`${month} is an invalid month`)
} else {
month;
}
if (day < 10) {
day = "0" + day;
} if (day > 31) {
return (`${day} is an invalid month`);
}else {
day;
}
let fullDate = `${year}-${month}-${day}`;
let dateRegex = /^([12]d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]d|3[01]))$/;
if (dateRegex.test(fullDate) == false) {
isDOBValid;
} else if (dateRegex.test(fullDate) == true) {
isDOBValid = true;
}
return isDOBValid;

}
console.log(isYearCorrect("970812"))
console.log(isYearCorrect("721329"))

Answer 1

在将string转换为日期之前，您需要设置验证检查条件。

function isYearCorrect(string) {
let yearPiece = +string.substring(0, 2);
let monthPiece = +string.substring(2, 4);
let dayPiece = +string.substring(4, 6);

if (monthPiece > 12) {
return (`${monthPiece} is an invalid month`)
}

if (dayPiece > 31) {
return (`${dayPiece} is an invalid month`);
}
let dateOfBirth = new Date(yearPiece, monthPiece, dayPiece)
let year = dateOfBirth.getFullYear();
let month = dateOfBirth.getMonth()  + 1;
let day = dateOfBirth.getDate();
let isDOBValid = false;
/**This statement does not check to see if the month ranges from 1 - 12 but it skips
to the next year and month and leaves the day as is. Basically 971315 becomes 1998-01-15*/
if (month < 10) {
month = "0" + monthPiece;
}
if (day < 10) {
day = "0" + day;
} 
let fullDate = `${year}-${month}-${day}`;
let dateRegex = /^([12]d{3}-(0[1-9]|1[0-2])-(0[1-9]|[12]d|3[01]))$/;
if (dateRegex.test(fullDate)) {
isDOBValid = true;
}
return isDOBValid;

}
console.log(isYearCorrect("970812"))
console.log(isYearCorrect("721329"))

Answer 2

TLDR：按设计工作。

解决方案是在将字符串放入新的Date构造函数之前解析字符串，因为您试图做的事情在某种程度上已经由Date对象完成了。

正在发生的事情是，日期是"；聪明的"；它防止无效日期并触发内部机制，因此当您例如用值"调用此函数时；721429"；这被认为是无效的；1973-3-1"；。这是正确的(记住二月更短(。

在这里，您可以阅读更多关于日期本身及其可接受的构造函数的信息：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/Date

更重要的是，我建议不要使用"；字符串"；作为变量的名称，并在可能的情况下使用const(例如regex或fullDate变量(。