Javascript Regexp dynamic generation from variables

Question

How to construct two regex patterns into one   For example I have one long pattern and one smaller  I need to put smaller one in front of long one   var pattern1              -     var pattern2              -             -    str match     pattern1     pattern2   gi      This doesn t work  When I m concatenating strings  all slashes are gone

User · Accepted Answer

You have to use RegExp   str match new RegExp pattern1     pattern2   gi            When I m concatenating strings  all slashes are gone    If you have a backslash in your pattern to escape a special regex character   like      you have to use two backslashes in the string  because   is the escape character in a string   new RegExp        would be the same as        So your patterns have to become   var pattern1                -      var pattern2                -                -

User · Answer

Use the below   var regEx   new RegExp pattern1     pattern2   gi     str match regEx

User · Answer

You have to forgo the regex literal and use the object constructor  where you can pass the regex as a string   var regex   new RegExp pattern1     pattern2   gi    str match regex

User · Answer

The RegExp constructor creates a regular expression object for matching text with a pattern       var pattern1                -          var pattern2                -                -          var regex   new RegExp pattern1         pattern2   gi        str match regex     Above code works perfectly for me

[javascript] Javascript Regexp dynamic generation from variables?

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