How to use JavaScript regex over multiple lines

Question

var ss    lt pre gt aaaa nbbb nccc lt  pre gt ddd   var arr  ss match    lt pre    lt   pre gt  gm    alert arr          null   I d want the PRE block be picked up  even though it spans over newline characters  I thought the  m  flag does it  Does not   Found the answer here before posting  SInce I thought I knew JavaScript  read three books  worked hours  and there wasn t an existing solution at SO  I ll dare to post anyways  throw stones here  So the solution is   var ss    lt pre gt aaaa nbbb nccc lt  pre gt ddd   var arr  ss match    lt pre  s S    lt   pre gt  gm    alert arr           lt pre gt     lt  pre gt       Does anyone have a less cryptic way   Edit  this is a duplicate but since it s harder to find than mine  I don t remove   It proposes     as a  multiline dot   What I still don t understand is why    n  does not work  Guess this is one of the sad parts of JavaScript

User · Answer

In addition to above-said examples  it is an alternate       w  s      Where  w is for words and  s is for white spaces

User · Answer

DON T use      r n   instead of   for multiline matching   DO use   s S  instead of   for multiline matching  Also  avoid greediness where not needed by using    or    quantifier instead of   or    This can have a huge performance impact   See the benchmark I have made  http   jsperf com javascript-multiline-regexp-workarounds  Using      fastest Using   s S   0 83  slower Using     r  n   96  slower Using      r n    96  slower   NB  You can also use     but it is deprecated in the below comment

User · Answer

w  s    This one was beyond helpful for me  especially for matching multiple things that include new lines  every single other answer ended up just grouping all of the matches together

User · Answer

n  doesn t work  because dot in     by regex definition  not javascript only  means the dot-character  You can use     n   or      n r    instead

User · Answer

You do not specify your environment and version of Javascript  ECMAscript   and I realise this post was from 2009  but just for completeness  with the release of ECMA2018 we can now use the s flag to cause   to match   n   see https   stackoverflow com a 36006948 141801  Thus   let s    I am a string nover several nlines    console log  String       s           let r    string  several  lines s     Note  s  modifier console log  Match      r test s       test  returns true   This is a recent addition and will not work in many current environments  for example Node v8 7 0 does not seem to recognise it  but it works in Chromium  and I m using it in a Typescript test I m writing and presumably it will become more mainstream as time goes by

User · Answer

I have tested it  Chrome  and it working for me  both     and    0    by changing the dot     by either    0  or       because dot doesn t match line break  See here  http   www regular-expressions info dot html      x000D   x000D  var ss    lt pre gt aaaa nbbb nccc lt  pre gt ddd   x000D  var arr  ss match    lt pre   0    lt   pre gt  gm    x000D  alert arr         Working x000D   x000D   x000D

User · Answer

Now there s the s  single line  modifier  that lets the dot matches new lines as well     s will also match new lines  D Just add the s behind the slash    lt pre    lt   pre gt  gms

User · Answer

n  does not work because   has no special meaning inside of     it just means a literal        n  would be a way to specify  any character  including a newline   If you want to match all newlines  you would need to add  r as well to include Windows and classic Mac OS style line endings       r n     That turns out to be somewhat cumbersome  as well as slow   see KrisWebDev s answer for details   so a better approach would be to match all whitespace characters and all non-whitespace characters  with   s S   which will match everything  and is faster and simpler   In general  you shouldn t try to use a regexp to match the actual HTML tags  See  for instance  these questions for more information on why   Instead  try actually searching the DOM for the tag you need  using jQuery makes this easier  but you can always do document getElementsByTagName  pre   with the standard DOM   and then  search the text content of those results with a regexp if you need to match against the contents

[javascript] How to use JavaScript regex over multiple lines?

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