How to extract a string using JavaScript Regex

Question

I m trying to extract a substring from a file with JavaScript Regex  Here is a slice from the file    DATE 20091201T220000 SUMMARY Dad s birthday   the field I want to extract is  Summary   Here is the approach   extractSummary   function iCalContent           input   iCal file content   return   Event summary        var arr   iCalContent match   SUMMARY        g     return arr

User · Accepted Answer

You need to use the m flag      multiline  treat beginning and end characters    and    as working   over multiple lines  i e   match the beginning or end of each line    delimited by  n or  r   not only the very beginning or end of the   whole input string    Also put the   in the right place    DATE 20091201T220000 r nSUMMARY Dad s birthday  match   SUMMARY        gm     ------------------------------------------------------------------         -----------------------------------------------------------------------

User · Answer

Your regular expression most likely wants to be    nSUMMARY       g   A helpful little trick I like to use is to default assign on match with an array   var arr   iCalContent match   nSUMMARY       g             could also use null for empty value return arr 0     This way you don t get annoying type errors when you go to use arr

User · Answer

this is how you can parse iCal files with javascript      function calParse str             function parse                 var obj                   while str length                    var p   str shift   split                       var k   p shift    p   p join                    switch k                        case  BEGIN                           obj p    parse                            break                      case  END                           return obj                      default                          obj k    p                                              return obj                    str   str replace   n  g       split   n            return parse   VCALENDAR             example         BEGIN VCALENDAR n        VERSION 2 0 n        PRODID -  hacksw handcal  NONSGML v1 0  EN n        BEGIN VEVENT n        DTSTART 19970714T170000Z n        DTEND 19970715T035959Z n        SUMMARY Bastille Day Party n        END VEVENT n        END VCALENDAR n        cal   calParse example       alert cal VEVENT SUMMARY

User · Answer

This code works    let str    quot governance string i want  quot      let res   str match    governance             g    res will equal  quot string i want quot   However  in this example res is still an array  so do not treat res like a string  By grouping the characters I do not want  using   string   and matching on what is between the brackets  the code extracts the string I want  You can try it out here  https   www w3schools com jsref tryit asp filename tryjsref match regexp Good luck

User · Answer

function extractSummary iCalContent      var rx     nSUMMARY      n g    var arr   rx exec iCalContent     return arr 1        You need these changes    Put the   inside the parenthesis as suggested above  Otherwise your matching group will contain only one character   Get rid of the   and    With the global option they match on start and end of the full string  rather than on start and end of lines  Match on explicit newlines instead  I suppose you want the matching group  what s inside the parenthesis  rather than the full array  arr 0  is the full match    nSUMMARY       and the next indexes contain the group matches  String match regexp  is supposed to return an array with the matches  In my browser it doesn t  Safari on Mac returns only the full match  not the groups   but Regexp exec string  works

User · Answer

instead of      would be a start  The latter will only capture the last character on the line   Also  no need to escape the

[javascript] How to extract a string using JavaScript Regex?

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