How do you access the matched groups in a JavaScript regular expression

Question

I want to match a portion of a string using a regular expression and then access that parenthesized substring   var myString    something format abc      I want  abc   var arr          s format          s     exec myString    console log arr          Prints     format abc    abc      so far so good  console log arr 1        Prints  undefined        console log arr 0        Prints  format undefined         What am I doing wrong     I ve discovered that there was nothing wrong with the regular expression code above  the actual string which I was testing against was this    date format  A    Reporting that   A  is undefined seems a very strange behaviour  but it is not directly related to this question  so I ve opened a new one  Why is a matched substring returning  undefined  in JavaScript      The issue was that console log takes its parameters like a printf statement  and since the string I was logging    A   had a special value  it was trying to find the value of the next parameter

User · Answer

Your syntax probably isn t the best to keep  FF Gecko defines RegExp as an extension of Function   FF2 went as far as typeof  pattern       function    It seems this is specific to FF -- IE  Opera  and Chrome all throw exceptions for it   Instead  use either method previously mentioned by others  RegExp exec or String match  They offer the same results   var regex          s format          s      var input    something format abc    regex input              gt     format abc    abc   regex exec input         gt     format abc    abc   input match regex        gt     format abc    abc

User · Answer

Here   s a method you can use to get the n th capturing group for each match    x000D   x000D  function getMatches string  regex  index    x000D    index     index   1      default to the first capturing group x000D    var matches       x000D    var match  x000D    while  match   regex exec string     x000D      matches push match index    x000D      x000D    return matches  x000D    x000D   x000D   x000D     Example   x000D  var myString    something format abc something format def something format ghi   x000D  var myRegEx          s format          s    g  x000D   x000D     Get an array containing the first capturing group for every match x000D  var matches   getMatches myString  myRegEx  1   x000D   x000D     Log results x000D  document write matches length     matches found      JSON stringify matches   x000D  console log matches   x000D   x000D   x000D

User · Answer

Regex function for extracting object from  window location search  string       var search     a 3 amp b 4 amp c 7      Example search string  var getSearchObj   function  searchString         var match  key  value  obj           var pattern      w     w   g      var search   searchString substr 1      Remove          while  match   pattern exec search             obj match 0  split      0     match 0  split      1              return obj       console log getSearchObj search

User · Answer

x000D   x000D  var myString    something format abc   x000D  var arr   myString match   bformat       b    x000D  console log arr 0          arr 1    x000D   x000D   x000D    The  b isn t exactly the same thing   It works on --format foo   but doesn t work on format a b  But I wanted to show an alternative to your expression  which is fine  Of course  the match call is the important thing

User · Answer

I you are like me and wish regex would return an Object like this         match             matchAtIndex  0      capturedGroups                       then snip the function from below   x000D   x000D      x000D      param  string   number  input x000D              The input string to match x000D      param  regex   string   expression x000D              Regular expression  x000D      param  string  flags x000D              Optional Flags x000D      x000D      returns  array  x000D        x000D      match         x000D      matchAtIndex  0  x000D      capturedGroups                   x000D            x000D      x000D  function regexMatch input  expression  flags    g     x000D    let regex   expression instanceof RegExp   expression   new RegExp expression  flags  x000D    let matches   input matchAll regex  x000D    matches       matches  x000D    return matches map item   gt    x000D      return   x000D        match  item 0   x000D        matchAtIndex  item index  x000D        capturedGroups  item length  gt  1   item slice 1    undefined x000D        x000D       x000D    x000D   x000D  let input    key1 value1  key2 value2   x000D  let regex      w     w   g x000D   x000D  let matches   regexMatch input  regex  x000D   x000D  console log matches  x000D   x000D   x000D

User · Answer

We can access the matched group in a regular expressions by using backslash followed by number of the matching group       a-z   1    In the code  1 represented matched by first group   a-z

User · Answer

Your syntax probably isn t the best to keep  FF Gecko defines RegExp as an extension of Function   FF2 went as far as typeof  pattern       function    It seems this is specific to FF -- IE  Opera  and Chrome all throw exceptions for it   Instead  use either method previously mentioned by others  RegExp exec or String match  They offer the same results   var regex          s format          s      var input    something format abc    regex input              gt     format abc    abc   regex exec input         gt     format abc    abc   input match regex        gt     format abc    abc

User · Answer

x000D   x000D  var myString    something format abc   x000D  var arr   myString match   bformat       b    x000D  console log arr 0          arr 1    x000D   x000D   x000D    The  b isn t exactly the same thing   It works on --format foo   but doesn t work on format a b  But I wanted to show an alternative to your expression  which is fine  Of course  the match call is the important thing

User · Answer

One line solution   const matches    text regex    gt      text matchAll regex   map   match    gt match    So you can use this way  must use  g    matches  something format abc          s format          s    g    result      format abc

User · Answer

You can access capturing groups like this    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  var match   myRegexp exec myString   x000D  console log match 1       abc x000D   x000D   x000D    And if there are multiple matches you can iterate over them    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  match   myRegexp exec myString   x000D  while  match    null    x000D       matched text  match 0  x000D       match start  match index x000D       capturing group n  match n  x000D    console log match 0   x000D    match   myRegexp exec myString   x000D    x000D   x000D   x000D    Edit  2019-09-10  As you can see the way to iterate over multiple matches was not very intuitive  This lead to the proposal of the String prototype matchAll method  This new method is expected to ship in the ECMAScript 2020 specification  It gives us a clean API and solves multiple problems  It has been started to land on major browsers and JS engines as Chrome 73    Node 12  and Firefox 67    The method returns an iterator and is used as follows    x000D   x000D  const string    something format abc   x000D  const regexp          s format          s    g  x000D  const matches   string matchAll regexp   x000D       x000D  for  const match of matches    x000D    console log match   x000D    console log match index  x000D    x000D   x000D   x000D    As it returns an iterator  we can say it s lazy  this is useful when handling particularly large numbers of capturing groups  or very large strings  But if you need  the result can be easily transformed into an Array by using the spread syntax or the Array from method   function getFirstGroup regexp  str      const array       str matchAll regexp      return array map m   gt  m 1          or  function getFirstGroup regexp  str      return Array from str matchAll regexp   m   gt  m 1        In the meantime  while this proposal gets more wide support  you can use the official shim package   Also  the internal workings of the method are simple  An equivalent implementation using a generator function would be as follows   function  matchAll str  regexp      const flags   regexp global   regexp flags   regexp flags    g     const re   new RegExp regexp  flags     let match    while  match   re exec str         yield match          A copy of the original regexp is created  this is to avoid side-effects due to the mutation of the lastIndex property when going through the multple matches   Also  we need to ensure the regexp has the global flag to avoid an infinite loop   I m also happy to see that even this StackOverflow question was referenced in the discussions of the proposal

User · Answer

Using your code   console log arr 1        prints  abc console log arr 0        prints   format abc   Edit  Safari 3  if it matters

User · Answer

With es2018 you can now String match   with named groups  makes your regex more explicit of what it was trying to do   const url      https   stackoverflow com questions 432493 how-do-you-access-the-matched-groups-in-a-javascript-regular-expression some parameter   const regex       lt protocol gt https          lt hostname gt   w-          lt pathname gt   w-            lt querystring gt          const   groups  segments     url match regex   console log segments     and you ll get something like                   protocol   https   hostname   stackoverflow com   pathname   questions 432493 how-do-you-access-the-matched-groups-in-a-javascript-regular-expression   querystring   some parameter

User · Answer

You can access capturing groups like this    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  var match   myRegexp exec myString   x000D  console log match 1       abc x000D   x000D   x000D    And if there are multiple matches you can iterate over them    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  match   myRegexp exec myString   x000D  while  match    null    x000D       matched text  match 0  x000D       match start  match index x000D       capturing group n  match n  x000D    console log match 0   x000D    match   myRegexp exec myString   x000D    x000D   x000D   x000D    Edit  2019-09-10  As you can see the way to iterate over multiple matches was not very intuitive  This lead to the proposal of the String prototype matchAll method  This new method is expected to ship in the ECMAScript 2020 specification  It gives us a clean API and solves multiple problems  It has been started to land on major browsers and JS engines as Chrome 73    Node 12  and Firefox 67    The method returns an iterator and is used as follows    x000D   x000D  const string    something format abc   x000D  const regexp          s format          s    g  x000D  const matches   string matchAll regexp   x000D       x000D  for  const match of matches    x000D    console log match   x000D    console log match index  x000D    x000D   x000D   x000D    As it returns an iterator  we can say it s lazy  this is useful when handling particularly large numbers of capturing groups  or very large strings  But if you need  the result can be easily transformed into an Array by using the spread syntax or the Array from method   function getFirstGroup regexp  str      const array       str matchAll regexp      return array map m   gt  m 1          or  function getFirstGroup regexp  str      return Array from str matchAll regexp   m   gt  m 1        In the meantime  while this proposal gets more wide support  you can use the official shim package   Also  the internal workings of the method are simple  An equivalent implementation using a generator function would be as follows   function  matchAll str  regexp      const flags   regexp global   regexp flags   regexp flags    g     const re   new RegExp regexp  flags     let match    while  match   re exec str         yield match          A copy of the original regexp is created  this is to avoid side-effects due to the mutation of the lastIndex property when going through the multple matches   Also  we need to ensure the regexp has the global flag to avoid an infinite loop   I m also happy to see that even this StackOverflow question was referenced in the discussions of the proposal

User · Answer

x000D   x000D  function getMatches string  regex  index    x000D    index     index   1      default to the first capturing group x000D    var matches       x000D    var match  x000D    while  match   regex exec string     x000D      matches push match index    x000D      x000D    return matches  x000D    x000D   x000D   x000D     Example   x000D  var myString    Rs 200 is Debited to A c    2031 on 02-12-14 20 05 49  Clear Bal Rs 66248 77  AT ATM  TollFree 1800223344 18001024455  6am-10pm    x000D  var myRegEx    clear bal     d     d 2   gi  x000D   x000D     Get an array containing the first capturing group for every match x000D  var matches   getMatches myString  myRegEx  1   x000D   x000D     Log results x000D  document write matches length     matches found      JSON stringify matches   x000D  console log matches   x000D   x000D   x000D     x000D   x000D  function getMatches string  regex  index    x000D    index     index   1      default to the first capturing group x000D    var matches       x000D    var match  x000D    while  match   regex exec string     x000D      matches push match index    x000D      x000D    return matches  x000D    x000D   x000D   x000D     Example   x000D  var myString    something format abc something format def something format ghi   x000D  var myRegEx          s format          s    g  x000D   x000D     Get an array containing the first capturing group for every match x000D  var matches   getMatches myString  myRegEx  1   x000D   x000D     Log results x000D  document write matches length     matches found      JSON stringify matches   x000D  console log matches   x000D   x000D   x000D

User · Answer

Get all group occurrence    x000D   x000D  let m     s    something format abc  format def  format ghi   x000D   x000D  s replace        s format          s    g   x y   gt  m push y    x000D   x000D  console log m   x000D   x000D   x000D

User · Answer

You can access capturing groups like this    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  var match   myRegexp exec myString   x000D  console log match 1       abc x000D   x000D   x000D    And if there are multiple matches you can iterate over them    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  match   myRegexp exec myString   x000D  while  match    null    x000D       matched text  match 0  x000D       match start  match index x000D       capturing group n  match n  x000D    console log match 0   x000D    match   myRegexp exec myString   x000D    x000D   x000D   x000D    Edit  2019-09-10  As you can see the way to iterate over multiple matches was not very intuitive  This lead to the proposal of the String prototype matchAll method  This new method is expected to ship in the ECMAScript 2020 specification  It gives us a clean API and solves multiple problems  It has been started to land on major browsers and JS engines as Chrome 73    Node 12  and Firefox 67    The method returns an iterator and is used as follows    x000D   x000D  const string    something format abc   x000D  const regexp          s format          s    g  x000D  const matches   string matchAll regexp   x000D       x000D  for  const match of matches    x000D    console log match   x000D    console log match index  x000D    x000D   x000D   x000D    As it returns an iterator  we can say it s lazy  this is useful when handling particularly large numbers of capturing groups  or very large strings  But if you need  the result can be easily transformed into an Array by using the spread syntax or the Array from method   function getFirstGroup regexp  str      const array       str matchAll regexp      return array map m   gt  m 1          or  function getFirstGroup regexp  str      return Array from str matchAll regexp   m   gt  m 1        In the meantime  while this proposal gets more wide support  you can use the official shim package   Also  the internal workings of the method are simple  An equivalent implementation using a generator function would be as follows   function  matchAll str  regexp      const flags   regexp global   regexp flags   regexp flags    g     const re   new RegExp regexp  flags     let match    while  match   re exec str         yield match          A copy of the original regexp is created  this is to avoid side-effects due to the mutation of the lastIndex property when going through the multple matches   Also  we need to ensure the regexp has the global flag to avoid an infinite loop   I m also happy to see that even this StackOverflow question was referenced in the discussions of the proposal

User · Answer

You don t really need an explicit loop to parse multiple matches     pass a replacement function as the second argument as described in  String prototype replace regex  func     x000D   x000D  var str    Our chief weapon is  1    0  and  2      x000D  var params    surprise    fear    ruthless efficiency    x000D  var patt              g  x000D   x000D  str str replace patt  function m0  m1  position  return params parseInt m1       x000D   x000D  document write str   x000D   x000D   x000D    The m0 argument represents the full matched substring  0    1   etc  m1 represents the first matching group  i e  the part enclosed in brackets in the regex which is 0 for the first match  And position is the starting index within the string where the matching group was found     unused in this case

User · Answer

As  cms said in ECMAScript  ECMA-262  you can use matchAll  It return an iterator and by putting it in         spread operator  it converts to an array  this regex extract urls of file names   x000D   x000D  let text     lt a href  http   myhost com myfile 01 mp4  gt File1 lt  a gt   lt a href  http   myhost com myfile 02 mp4  gt File2 lt  a gt     let fileUrls       text matchAll  href   http              w 3     g   map r   gt  r 1     console log fileUrls   x000D   x000D   x000D

User · Answer

Your code works for me  FF3 on Mac  even if I agree with PhiLo that the regex should probably be     bformat       b     But  of course  I m not sure because I don t know the context of the regex

User · Answer

JUST USE RegExp  1    n th group eg   1 To match 1st group RegExp  1   To match 2nd group RegExp  2   if you use 3 group in regex likey note use after string match regex    RegExp  1 RegExp  2 RegExp  3   x000D   x000D   var str    The rain in   india  stays safe    x000D    var res   str match             ig   x000D      i used only one group in above example so RegExp  1 x000D  console log RegExp  1  x000D   x000D   x000D     x000D   x000D    easiest way is use RegExp  1 1st group in regex and 2nd grounp like x000D     RegExp  2 if exist use after match x000D   x000D  var regex             ig  x000D  var str    The rain in   SPAIN  stays   mainly  in the plain    x000D    var res   str match regex   x000D  for  const match of res    x000D    var res   match match regex   x000D    console log match   x000D    console log RegExp  1  x000D    x000D    x000D   x000D   x000D

User · Answer

A one liner that is practical only if you have a single pair of parenthesis   while     match   myRegex exec  myStr      amp  amp  matches push  match 1

User · Answer

There is no need to invoke the exec method  You can use  match  method directly on the string  Just don t forget the parentheses   var str    This is cool   var matches   str match   This is   cool      console log  JSON stringify matches        will print   This is cool   This is    cool   or something like that      Position 0 has a string with all the results  Position 1 has the first match represented by parentheses  and position 2 has the second match isolated in your parentheses  Nested parentheses are tricky  so beware

User · Answer

Your code works for me  FF3 on Mac  even if I agree with PhiLo that the regex should probably be     bformat       b     But  of course  I m not sure because I don t know the context of the regex

User · Answer

We can access the matched group in a regular expressions by using backslash followed by number of the matching group       a-z   1    In the code  1 represented matched by first group   a-z

User · Answer

String matchAll  see the Stage 3 Draft   December 7  2018 proposal   simplifies acccess to all groups in the match object  mind that Group 0 is the whole match  while further groups correspond to the capturing groups in the pattern       With matchAll available  you can avoid the while loop and exec with  g    Instead  by using matchAll  you get back an iterator which you can use with the more convenient for   of  array spread  or Array from   constructs   This method yields a similar output to Regex Matches in C   re finditer in Python  preg match all in PHP   See a JS demo  tested in Google Chrome 73 0 3683 67  official build   beta  64-bit      x000D   x000D  var myString    key1 value1  key2-value2   key3 value3   x000D  var matches   myString matchAll    w     -   w   g   x000D  console log     matches       All match with capturing group values x000D   x000D   x000D    The console log     matches   shows    You may also get match value or specific group values using   x000D   x000D  let matchData    key1 value1  key2-value2   key3 value3  matchAll    w     -   w   g  x000D  var matches       matchData      Note matchAll result is not re-iterable x000D   x000D  console log Array from matches  m   gt  m 0        All match  Group 0  values x000D       gt     key1 value1    key2-value2    key3 value3    x000D  console log Array from matches  m   gt  m 1        All match  Group 1  values x000D       gt     key1    key2    key3    x000D   x000D   x000D    NOTE  See the browser compatibility details

User · Answer

You can access capturing groups like this    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  var match   myRegexp exec myString   x000D  console log match 1       abc x000D   x000D   x000D    And if there are multiple matches you can iterate over them    x000D   x000D  var myString    something format abc   x000D  var myRegexp          s format          s    g  x000D  match   myRegexp exec myString   x000D  while  match    null    x000D       matched text  match 0  x000D       match start  match index x000D       capturing group n  match n  x000D    console log match 0   x000D    match   myRegexp exec myString   x000D    x000D   x000D   x000D    Edit  2019-09-10  As you can see the way to iterate over multiple matches was not very intuitive  This lead to the proposal of the String prototype matchAll method  This new method is expected to ship in the ECMAScript 2020 specification  It gives us a clean API and solves multiple problems  It has been started to land on major browsers and JS engines as Chrome 73    Node 12  and Firefox 67    The method returns an iterator and is used as follows    x000D   x000D  const string    something format abc   x000D  const regexp          s format          s    g  x000D  const matches   string matchAll regexp   x000D       x000D  for  const match of matches    x000D    console log match   x000D    console log match index  x000D    x000D   x000D   x000D    As it returns an iterator  we can say it s lazy  this is useful when handling particularly large numbers of capturing groups  or very large strings  But if you need  the result can be easily transformed into an Array by using the spread syntax or the Array from method   function getFirstGroup regexp  str      const array       str matchAll regexp      return array map m   gt  m 1          or  function getFirstGroup regexp  str      return Array from str matchAll regexp   m   gt  m 1        In the meantime  while this proposal gets more wide support  you can use the official shim package   Also  the internal workings of the method are simple  An equivalent implementation using a generator function would be as follows   function  matchAll str  regexp      const flags   regexp global   regexp flags   regexp flags    g     const re   new RegExp regexp  flags     let match    while  match   re exec str         yield match          A copy of the original regexp is created  this is to avoid side-effects due to the mutation of the lastIndex property when going through the multple matches   Also  we need to ensure the regexp has the global flag to avoid an infinite loop   I m also happy to see that even this StackOverflow question was referenced in the discussions of the proposal

User · Answer

x000D   x000D  function getMatches string  regex  index    x000D    index     index   1      default to the first capturing group x000D    var matches       x000D    var match  x000D    while  match   regex exec string     x000D      matches push match index    x000D      x000D    return matches  x000D    x000D   x000D   x000D     Example   x000D  var myString    Rs 200 is Debited to A c    2031 on 02-12-14 20 05 49  Clear Bal Rs 66248 77  AT ATM  TollFree 1800223344 18001024455  6am-10pm    x000D  var myRegEx    clear bal     d     d 2   gi  x000D   x000D     Get an array containing the first capturing group for every match x000D  var matches   getMatches myString  myRegEx  1   x000D   x000D     Log results x000D  document write matches length     matches found      JSON stringify matches   x000D  console log matches   x000D   x000D   x000D     x000D   x000D  function getMatches string  regex  index    x000D    index     index   1      default to the first capturing group x000D    var matches       x000D    var match  x000D    while  match   regex exec string     x000D      matches push match index    x000D      x000D    return matches  x000D    x000D   x000D   x000D     Example   x000D  var myString    something format abc something format def something format ghi   x000D  var myRegEx          s format          s    g  x000D   x000D     Get an array containing the first capturing group for every match x000D  var matches   getMatches myString  myRegEx  1   x000D   x000D     Log results x000D  document write matches length     matches found      JSON stringify matches   x000D  console log matches   x000D   x000D   x000D

User · Answer

Last but not least  I found one line of code that worked fine for me  JS ES6     x000D   x000D  let reg        S    igm     Get hashtags  x000D  let string    mi alegr  a es total    n fiestasdefindea  o  PadreHijo  buenosmomentos  france  paris   x000D   x000D  let matches    string match reg         map e   gt  e replace reg    1     x000D  console log matches   x000D   x000D   x000D    This will return     fiestasdefindea  o    PadreHijo    buenosmomentos    france    paris

User · Answer

Your syntax probably isn t the best to keep  FF Gecko defines RegExp as an extension of Function   FF2 went as far as typeof  pattern       function    It seems this is specific to FF -- IE  Opera  and Chrome all throw exceptions for it   Instead  use either method previously mentioned by others  RegExp exec or String match  They offer the same results   var regex          s format          s      var input    something format abc    regex input              gt     format abc    abc   regex exec input         gt     format abc    abc   input match regex        gt     format abc    abc

User · Answer

x000D   x000D  var myString    something format abc   x000D  var arr   myString match   bformat       b    x000D  console log arr 0          arr 1    x000D   x000D   x000D    The  b isn t exactly the same thing   It works on --format foo   but doesn t work on format a b  But I wanted to show an alternative to your expression  which is fine  Of course  the match call is the important thing

User · Answer

You don t really need an explicit loop to parse multiple matches     pass a replacement function as the second argument as described in  String prototype replace regex  func     x000D   x000D  var str    Our chief weapon is  1    0  and  2      x000D  var params    surprise    fear    ruthless efficiency    x000D  var patt              g  x000D   x000D  str str replace patt  function m0  m1  position  return params parseInt m1       x000D   x000D  document write str   x000D   x000D   x000D    The m0 argument represents the full matched substring  0    1   etc  m1 represents the first matching group  i e  the part enclosed in brackets in the regex which is 0 for the first match  And position is the starting index within the string where the matching group was found     unused in this case

User · Answer

As  cms said in ECMAScript  ECMA-262  you can use matchAll  It return an iterator and by putting it in         spread operator  it converts to an array  this regex extract urls of file names   x000D   x000D  let text     lt a href  http   myhost com myfile 01 mp4  gt File1 lt  a gt   lt a href  http   myhost com myfile 02 mp4  gt File2 lt  a gt     let fileUrls       text matchAll  href   http              w 3     g   map r   gt  r 1     console log fileUrls   x000D   x000D   x000D

User · Answer

String matchAll  see the Stage 3 Draft   December 7  2018 proposal   simplifies acccess to all groups in the match object  mind that Group 0 is the whole match  while further groups correspond to the capturing groups in the pattern       With matchAll available  you can avoid the while loop and exec with  g    Instead  by using matchAll  you get back an iterator which you can use with the more convenient for   of  array spread  or Array from   constructs   This method yields a similar output to Regex Matches in C   re finditer in Python  preg match all in PHP   See a JS demo  tested in Google Chrome 73 0 3683 67  official build   beta  64-bit      x000D   x000D  var myString    key1 value1  key2-value2   key3 value3   x000D  var matches   myString matchAll    w     -   w   g   x000D  console log     matches       All match with capturing group values x000D   x000D   x000D    The console log     matches   shows    You may also get match value or specific group values using   x000D   x000D  let matchData    key1 value1  key2-value2   key3 value3  matchAll    w     -   w   g  x000D  var matches       matchData      Note matchAll result is not re-iterable x000D   x000D  console log Array from matches  m   gt  m 0        All match  Group 0  values x000D       gt     key1 value1    key2-value2    key3 value3    x000D  console log Array from matches  m   gt  m 1        All match  Group 1  values x000D       gt     key1    key2    key3    x000D   x000D   x000D    NOTE  See the browser compatibility details

User · Answer

With es2018 you can now String match   with named groups  makes your regex more explicit of what it was trying to do   const url      https   stackoverflow com questions 432493 how-do-you-access-the-matched-groups-in-a-javascript-regular-expression some parameter   const regex       lt protocol gt https          lt hostname gt   w-          lt pathname gt   w-            lt querystring gt          const   groups  segments     url match regex   console log segments     and you ll get something like                   protocol   https   hostname   stackoverflow com   pathname   questions 432493 how-do-you-access-the-matched-groups-in-a-javascript-regular-expression   querystring   some parameter

User · Answer

There is no need to invoke the exec method  You can use  match  method directly on the string  Just don t forget the parentheses   var str    This is cool   var matches   str match   This is   cool      console log  JSON stringify matches        will print   This is cool   This is    cool   or something like that      Position 0 has a string with all the results  Position 1 has the first match represented by parentheses  and position 2 has the second match isolated in your parentheses  Nested parentheses are tricky  so beware

User · Answer

Using your code   console log arr 1        prints  abc console log arr 0        prints   format abc   Edit  Safari 3  if it matters

User · Answer

Terminology used in this answer    Match indicates the result of running your RegEx pattern against your string like so  someString match regexPattern   Matched patterns indicate all matched portions of the input string  which all reside inside the match array  These are all instances of your pattern inside the input string  Matched groups indicate all groups to catch  defined in the RegEx pattern   The patterns inside parentheses  like so   format       g  where       would be a matched group   These reside within matched patterns    Description  To get access to the matched groups  in each of the matched patterns  you need a function or something similar to iterate over the match  There are a number of ways you can do this  as many of the other answers show  Most other answers use a while loop to iterate over all matched patterns  but I think we all know the potential dangers with that approach  It is necessary to match against a new RegExp   instead of just the pattern itself  which only got mentioned in a comment  This is because the  exec   method behaves similar to a generator function     it stops every time there is a match  but keeps its  lastIndex to continue from there on the next  exec   call   Code examples  Below is an example of a function searchString which returns an Array of all matched patterns  where each match is an Array with all the containing matched groups  Instead of using a while loop  I have provided examples using both the Array prototype map   function as well as a more performant way     using a plain for-loop   Concise versions  less code  more syntactic sugar   These are less performant since they basically implement a forEach-loop instead of the faster for-loop      Concise ES6 ES2015 syntax const searchString         string  pattern    gt           string          match new RegExp pattern source  pattern flags            map match   gt               new RegExp pattern source  pattern flags               exec match        Or if you will  with ES5 syntax function searchString string  pattern        return string          match new RegExp pattern source  pattern flags            map match   gt              new RegExp pattern source  pattern flags               exec match       let string    something format abc       pattern          s format          s       let result   searchString string  pattern          format abc    abc    null     The trailing  null  disappears if you add the  global  flag   Performant versions  more code  less syntactic sugar      Performant ES6 ES2015 syntax const searchString    string  pattern    gt        let result            const matches   string match new RegExp pattern source  pattern flags         for  let i   0  i  lt  matches length  i              result push new RegExp pattern source  pattern flags  exec matches i                return result         Same thing  but with ES5 syntax function searchString string  pattern        var result            var matches   string match new RegExp pattern source  pattern flags         for  var i   0  i  lt  matches length  i              result push new RegExp pattern source  pattern flags  exec matches i                return result     let string    something format abc       pattern          s format          s       let result   searchString string  pattern          format abc    abc    null     The trailing  null  disappears if you add the  global  flag   I have yet to compare these alternatives to the ones previously mentioned in the other answers  but I doubt this approach is less performant and less fail-safe than the others

User · Answer

In regards to the multi-match parentheses examples above  I was looking for an answer here after not getting what I wanted from   var matches   mystring match     neededToMatchButNotWantedInResult  matchWanted  igm     After looking at the slightly convoluted function calls with while and  push   above  it dawned on me that the problem can be solved very elegantly with mystring replace   instead  the replacing is NOT the point  and isn t even done  the CLEAN  built-in recursive function call option for the second parameter is     var yourstring    something format abc something format def something format ghi    var matches       yourstring replace  format     s    igm  function m  p1   matches push p1          After this  I don t think I m ever going to use  match   for hardly anything ever again

User · Answer

A one liner that is practical only if you have a single pair of parenthesis   while     match   myRegex exec  myStr      amp  amp  matches push  match 1

User · Answer

JUST USE RegExp  1    n th group eg   1 To match 1st group RegExp  1   To match 2nd group RegExp  2   if you use 3 group in regex likey note use after string match regex    RegExp  1 RegExp  2 RegExp  3   x000D   x000D   var str    The rain in   india  stays safe    x000D    var res   str match             ig   x000D      i used only one group in above example so RegExp  1 x000D  console log RegExp  1  x000D   x000D   x000D     x000D   x000D    easiest way is use RegExp  1 1st group in regex and 2nd grounp like x000D     RegExp  2 if exist use after match x000D   x000D  var regex             ig  x000D  var str    The rain in   SPAIN  stays   mainly  in the plain    x000D    var res   str match regex   x000D  for  const match of res    x000D    var res   match match regex   x000D    console log match   x000D    console log RegExp  1  x000D    x000D    x000D   x000D   x000D

User · Answer

Your code works for me  FF3 on Mac  even if I agree with PhiLo that the regex should probably be     bformat       b     But  of course  I m not sure because I don t know the context of the regex

User · Answer

Terminology used in this answer    Match indicates the result of running your RegEx pattern against your string like so  someString match regexPattern   Matched patterns indicate all matched portions of the input string  which all reside inside the match array  These are all instances of your pattern inside the input string  Matched groups indicate all groups to catch  defined in the RegEx pattern   The patterns inside parentheses  like so   format       g  where       would be a matched group   These reside within matched patterns    Description  To get access to the matched groups  in each of the matched patterns  you need a function or something similar to iterate over the match  There are a number of ways you can do this  as many of the other answers show  Most other answers use a while loop to iterate over all matched patterns  but I think we all know the potential dangers with that approach  It is necessary to match against a new RegExp   instead of just the pattern itself  which only got mentioned in a comment  This is because the  exec   method behaves similar to a generator function     it stops every time there is a match  but keeps its  lastIndex to continue from there on the next  exec   call   Code examples  Below is an example of a function searchString which returns an Array of all matched patterns  where each match is an Array with all the containing matched groups  Instead of using a while loop  I have provided examples using both the Array prototype map   function as well as a more performant way     using a plain for-loop   Concise versions  less code  more syntactic sugar   These are less performant since they basically implement a forEach-loop instead of the faster for-loop      Concise ES6 ES2015 syntax const searchString         string  pattern    gt           string          match new RegExp pattern source  pattern flags            map match   gt               new RegExp pattern source  pattern flags               exec match        Or if you will  with ES5 syntax function searchString string  pattern        return string          match new RegExp pattern source  pattern flags            map match   gt              new RegExp pattern source  pattern flags               exec match       let string    something format abc       pattern          s format          s       let result   searchString string  pattern          format abc    abc    null     The trailing  null  disappears if you add the  global  flag   Performant versions  more code  less syntactic sugar      Performant ES6 ES2015 syntax const searchString    string  pattern    gt        let result            const matches   string match new RegExp pattern source  pattern flags         for  let i   0  i  lt  matches length  i              result push new RegExp pattern source  pattern flags  exec matches i                return result         Same thing  but with ES5 syntax function searchString string  pattern        var result            var matches   string match new RegExp pattern source  pattern flags         for  var i   0  i  lt  matches length  i              result push new RegExp pattern source  pattern flags  exec matches i                return result     let string    something format abc       pattern          s format          s       let result   searchString string  pattern          format abc    abc    null     The trailing  null  disappears if you add the  global  flag   I have yet to compare these alternatives to the ones previously mentioned in the other answers  but I doubt this approach is less performant and less fail-safe than the others

User · Answer

Your syntax probably isn t the best to keep  FF Gecko defines RegExp as an extension of Function   FF2 went as far as typeof  pattern       function    It seems this is specific to FF -- IE  Opera  and Chrome all throw exceptions for it   Instead  use either method previously mentioned by others  RegExp exec or String match  They offer the same results   var regex          s format          s      var input    something format abc    regex input              gt     format abc    abc   regex exec input         gt     format abc    abc   input match regex        gt     format abc    abc

User · Answer

Here   s a method you can use to get the n th capturing group for each match    x000D   x000D  function getMatches string  regex  index    x000D    index     index   1      default to the first capturing group x000D    var matches       x000D    var match  x000D    while  match   regex exec string     x000D      matches push match index    x000D      x000D    return matches  x000D    x000D   x000D   x000D     Example   x000D  var myString    something format abc something format def something format ghi   x000D  var myRegEx          s format          s    g  x000D   x000D     Get an array containing the first capturing group for every match x000D  var matches   getMatches myString  myRegEx  1   x000D   x000D     Log results x000D  document write matches length     matches found      JSON stringify matches   x000D  console log matches   x000D   x000D   x000D

User · Answer

Using your code   console log arr 1        prints  abc console log arr 0        prints   format abc   Edit  Safari 3  if it matters

User · Answer

I you are like me and wish regex would return an Object like this         match             matchAtIndex  0      capturedGroups                       then snip the function from below   x000D   x000D      x000D      param  string   number  input x000D              The input string to match x000D      param  regex   string   expression x000D              Regular expression  x000D      param  string  flags x000D              Optional Flags x000D      x000D      returns  array  x000D        x000D      match         x000D      matchAtIndex  0  x000D      capturedGroups                   x000D            x000D      x000D  function regexMatch input  expression  flags    g     x000D    let regex   expression instanceof RegExp   expression   new RegExp expression  flags  x000D    let matches   input matchAll regex  x000D    matches       matches  x000D    return matches map item   gt    x000D      return   x000D        match  item 0   x000D        matchAtIndex  item index  x000D        capturedGroups  item length  gt  1   item slice 1    undefined x000D        x000D       x000D    x000D   x000D  let input    key1 value1  key2 value2   x000D  let regex      w     w   g x000D   x000D  let matches   regexMatch input  regex  x000D   x000D  console log matches  x000D   x000D   x000D

User · Answer

x000D   x000D  var myString    something format abc   x000D  var arr   myString match   bformat       b    x000D  console log arr 0          arr 1    x000D   x000D   x000D    The  b isn t exactly the same thing   It works on --format foo   but doesn t work on format a b  But I wanted to show an alternative to your expression  which is fine  Of course  the match call is the important thing

User · Answer

Your code works for me  FF3 on Mac  even if I agree with PhiLo that the regex should probably be     bformat       b     But  of course  I m not sure because I don t know the context of the regex

User · Answer

In regards to the multi-match parentheses examples above  I was looking for an answer here after not getting what I wanted from   var matches   mystring match     neededToMatchButNotWantedInResult  matchWanted  igm     After looking at the slightly convoluted function calls with while and  push   above  it dawned on me that the problem can be solved very elegantly with mystring replace   instead  the replacing is NOT the point  and isn t even done  the CLEAN  built-in recursive function call option for the second parameter is     var yourstring    something format abc something format def something format ghi    var matches       yourstring replace  format     s    igm  function m  p1   matches push p1          After this  I don t think I m ever going to use  match   for hardly anything ever again

User · Answer

Regex function for extracting object from  window location search  string       var search     a 3 amp b 4 amp c 7      Example search string  var getSearchObj   function  searchString         var match  key  value  obj           var pattern      w     w   g      var search   searchString substr 1      Remove          while  match   pattern exec search             obj match 0  split      0     match 0  split      1              return obj       console log getSearchObj search

User · Answer

One line solution   const matches    text regex    gt      text matchAll regex   map   match    gt match    So you can use this way  must use  g    matches  something format abc          s format          s    g    result      format abc

User · Answer

Last but not least  I found one line of code that worked fine for me  JS ES6     x000D   x000D  let reg        S    igm     Get hashtags  x000D  let string    mi alegr  a es total    n fiestasdefindea  o  PadreHijo  buenosmomentos  france  paris   x000D   x000D  let matches    string match reg         map e   gt  e replace reg    1     x000D  console log matches   x000D   x000D   x000D    This will return     fiestasdefindea  o    PadreHijo    buenosmomentos    france    paris

User · Answer

Using your code   console log arr 1        prints  abc console log arr 0        prints   format abc   Edit  Safari 3  if it matters

User · Answer

Get all group occurrence    x000D   x000D  let m     s    something format abc  format def  format ghi   x000D   x000D  s replace        s format          s    g   x y   gt  m push y    x000D   x000D  console log m   x000D   x000D   x000D

[javascript] How do you access the matched groups in a JavaScript regular expression?

Examples related to javascript

Examples related to regex