Regex stop script error occur for long values

Question

First letter should be alpha/numeric and forward slash, every special characters are allowed except & and |

 new RegExp('^[\/A-Za-z0-9](([^\|\&]?[a-zA-Z0-9]?)*)$');

Above regex work for correct format and minimum characters e.g(/abcd%*)

If i give long character e.g( /abcdabcdabcdabcdabcdabcdabcd& ),stop script error occurs in firefox. Please suggest some better regex for fix it

It would be better if you tell us what string(s) you are trying to match. — Salman Arshad
– Salman Arshad, Commented Oct 8, 2015 at 11:06
@SalmanA Just look at the fiddle or the post. He's trying to match with /abcdabcdabcdabcdabcdabcdabcd& — Magus
– Magus, Commented Oct 8, 2015 at 11:08

benshepherd · Accepted Answer · 2015-10-08 11:18:28Z

4

Your issue is the capturing groups (brackets). Get rid of those and it's fine. Just make it as simple as you can!

First letter should be alpha/numeric [or] forward slash

^[/A-Za-z0-9]

every special characters are allowed except & and |

[^|&]+

(You don't need to escape | or &.)

Putting it together:

^[\/A-Za-z0-9][^|&]+$

Try it here.

answered Oct 8, 2015 at 11:12

benshepherd

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3 Comments

Besides the capturing groups, there is also a potential catastrophic backtracking issue with the original regex.

Don't need to escape / either (inside first bracket).

Oh yeah! I always thought you did... :)