Why does this RegExp cause the browser to crash?

Question

I was working on a RegExp and found out that if the string contains dash aa-bb.js and the query string part m=123, it will cause the browser to crash, apart from not being the best Regular Expression for this purpose, I'd like to know why does it work for https://example.org/aa.js and not for https://example.org/js/aa-bb.js?m=123

var re = /src=[\'|\"]([ -0-9a-zA-Z:]*[ 0-9a-zA-Z;]*)*[\'|\"]/g;
var result = re.exec("<script src='https://example.org/js/aa-bb.js?m=123'></script>");
console.log(result)

regex crash .. backtracking issues? look at [fixing-catastrophic-backtracking-in-regular-expression](https://stackoverflow.com/questions/45463148/fixing-catastrophic-backtracking-in-regular-expression) — Patrick Artner, May 05 '18 at 17:53

score 1 · Answer 1 · 2018-05-05T18:10:54.943

Besides your regex has other problems,
your error is this (which probably caused the crash):

Error: Regex Construction .. 

Invalid range end in character class

     src= [\'|\"] 
     (                             # (1 start)
          [ -0-<<<HERE>>>9a-zA-Z:]* 
          [ 0-9a-zA-Z;]* 
     )*                            # (1 end)
     [\'|\"]

In the class, the range <space> to 0, then a range operator without the starting character.

Why does this RegExp cause the browser to crash?

1 Answers1