获取字符前的部分子串

Question

我有一个网址，像这样：

https://www.example.com/exampletitle21sep11oct2020/index.html

我需要的部分是在最后一个和倒数第二个“/”字符之间。但我不需要整个部分，我特别需要最后一个“/”字符之前的最后日期。如您所见，有两个日期紧挨着，它们之间没有分隔符，因此很难使用substring或indexOf方法。更困难的是，第一个日期只包含日和月，而最后一个日期包含整个日期。

有什么方法可以让我从此网址中提取最后一个“/”字符之前的最后日期吗？

Answer 1

使用正则表达式，您可以获得第二个日期，如下所示：const regex = /\/(?:.*?(\d{1,2}\w{3}\d{0,4}))\/.*?$/;const [, date] = regex.exec("https://www.example.com/exampletitle21sep11oct2020/index.html");console.log({ date })const regex = /\/(?:.*?(\d{1,2}\w{3}\d{0,4}))\/.*?$/;const [, date] = regex.exec("https://www.example.com/exampletitle21sep9oct2020/index.html");console.log({ date });console.log(regex.exec("https://www.example.com/exampletitle21sep9oct/index.html")[1])

Answer 2

您可以找到并解析包含以下模式的路径：^         Line start.+        One or more of anything(\d{2})   2-digit date(\w{3})   3-letter month (lowercase)(\d{2})   2-digit date(\w{3})   3-letter month (lowercase)(\d{4})   4-digit year$         Line end例子我用moment来处理日期解析。const expression = /^.+(\d{2})(\w{3})(\d{2})(\w{3})(\d{4})$/;const format = 'DD MMM YYYY';const toTitleCase = (str) => str.charAt(0).toUpperCase() + str.slice(1);const parseDates = (path) => {  const url    = new URL(path),        tokens = url.pathname.split('/'),        found  = tokens.find(token => token.match(expression));  if (!found) return null;  const [    , startDate, startMonth, endDate, endMonth, year  ] = found.match(expression);  return {    start : moment(`${startDate} ${toTitleCase(startMonth)} ${year}`, format),    end   : moment(`${endDate} ${toTitleCase(endMonth)} ${year}`, format)  };};const dates = parseDates('https://www.example.com/exampletitle21sep11oct2020/index.html');console.log(dates);<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>展开片段

Answer 3

仅使用一个正则表达式，一切都会简单得多：var url = 'https://www.example.com/exampletitle21sep11oct2020/index.html'var res = url.match( /.*?(\d+[a-z]+\d{4})\/.*?$/i );// res === [ "https://www.example.com/exampletitle21sep11oct2020/index.html", "11oct2020" ]var endDate = res[1];// endDate === "11oct2020"或（但“exampletitle”不得以数字结尾）：var res = url.match( /.*?(\d+[a-z]+)(\d+[a-z]+)(\d{4})\/.*?$/i );// [ "https://www.example.com/exampletitle21sep11oct2020/index.html", "21sep", "11oct", "2020" ]或者：var res = url.match( /.*?(\d+)([a-z]+)(\d+)([a-z]+)(\d{4})\/.*?$/i );// [ "https://www.example.com/exampletitle21sep11oct2020/index.html", "21", "sep", "11", "oct", "2020" ]但是，如果您知道日期始终是 2 位数字（始终是“01”，而不是“1”），则“exampletitle”可以是任何字符串：var res = url.match( /.*?(\d{2}[a-z]+\d{4})\/.*?$/i );var res = url.match( /.*?(\d{2}[a-z]+)(\d+[a-z]+)(\d{4})\/.*?$/i );var res = url.match( /.*?(\d{2})([a-z]+)(\d+)([a-z]+)(\d{4})\/.*?$/i );

Answer 4

试试这个更新const url = "https://www.example.com/exampletitle21sep11oct2020/index.html";const urlData = url.split('/');const datePart = urlData[urlData.length-2];const res = datePart.slice(-9); <-- this will give you "11oct2020" -->