尝试改进日期验证的正则表达式

Question

我写了一个正则表达式来验证 MonthName dd, yyyy 格式的日期

下面的代码适用于 2 天数字的日期：

^(January|February|March|April|May|June|July|August|September|October|November|December)\s+\d\d[,]\s+(19|20)\d\d

对于日期只有一位的日期（例如：2015 年 4 月 5 日），我使用：

^(January|February|March|April|May|June|July|August|September|October|November|December)\s+\d[,]\s+(19|20)\d\d

如何将我的正则表达式更改为两个选项的单个正则表达式？ （2015 年 4 月 24 日和 2015 年 4 月 5 日）

Answer 1

符合您的代码的最简单方法：您只需说它应该是一位或两位数。我们可以在花括号内给出字符数。

\s+\d{1,2}[,]\s+(19|20)\d{2}

或者更详细的，如this answer

Answer 2

您的完整正则表达式可能如下所示：

/^(January|February|March|April|May|June|July|August|September|October|November|December)\s+(\d{1,2}),?\s+((?:19|20)\d{2})$/i

将匹配：

February 2 1976
August 11 2011
november 19 1966
march 11, 1945

Demo

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正则表达式解释：

/^(January|February|March|April|May|June|July|August|September|October|November|December)\s+(\d{1,2}),?\s+((?:19|20)\d{2})$/gmi

i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])

^ assert position at start of a line
1st Capturing group (January|February|March|April|May|June|July|August|September|October|November|December)
    1st Alternative: January
        January matches the characters January literally (case insensitive)
    2nd Alternative: February
        February matches the characters February literally (case insensitive)
    3rd Alternative: March
        March matches the characters March literally (case insensitive)
    4th Alternative: April
        April matches the characters April literally (case insensitive)
    5th Alternative: May
        May matches the characters May literally (case insensitive)
    6th Alternative: June
        June matches the characters June literally (case insensitive)
    7th Alternative: July
        July matches the characters July literally (case insensitive)
    8th Alternative: August
        August matches the characters August literally (case insensitive)
    9th Alternative: September
        September matches the characters September literally (case insensitive)
    10th Alternative: October
        October matches the characters October literally (case insensitive)
    11th Alternative: November
        November matches the characters November literally (case insensitive)
    12th Alternative: December
        December matches the characters December literally (case insensitive)
\s+ match any white space character [\r\n\t\f ]
    Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
2nd Capturing group (\d{1,2})
    \d{1,2} match a digit [0-9]
        Quantifier: {1,2} Between 1 and 2 times, as many times as possible, giving back as needed [greedy]
,? matches the character , literally
    Quantifier: ? Between zero and one time, as many times as possible, giving back as needed [greedy]
\s+ match any white space character [\r\n\t\f ]
    Quantifier: + Between one and unlimited times, as many times as possible, giving back as needed [greedy]
3rd Capturing group ((?:19|20)\d{2})
    (?:19|20) Non-capturing group
        1st Alternative: 19
            19 matches the characters 19 literally
        2nd Alternative: 20
            20 matches the characters 20 literally
    \d{2} match a digit [0-9]
        Quantifier: {2} Exactly 2 times
$ assert position at end of a line