CODEWITHSUNDEEP
javascriptregextags
HelpASisterOut
HelpASisterOut

Reputation: 3185

regex.test() freezes webpage

I am writing a function that extracts the parameters in a URL, and I am using regex to identify if an email is present in the URL in order to remove it.

Here is my function :

function redactEmail() {
  var emailRedacted = ""; 
  try {
        var urlparams= window.location.search.replace("?","");
        var urlparamsdecoded = decodeURIComponent(urlparams);
        emailRedacted = urlparamsdecoded; 
        var emailRegex = /\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+/; 
        if (emailRegex.test(urlparamsdecoded)) {
                emailRedacted = urlparamsdecoded.replace(emailRegex, '[REDACTED EMAIL]');
        }
  }
  catch (e) {}      
  return emailRedacted;
}

This worked to return this :

email=[REDACTED EMAIL]

from this :

https://www.test.com/[email protected]

But in some cases, this function is stopping the whole website from working.

I am using this function in a tag on a website in GTM so I don't have access to the source code of the website.

An example where the website stopped working is this :

https://www.test.com/?token=_JxY5kgHdKMkO8uSYf77sEl9mJhD7NHwAlrsMfJ-1zg

The website stopped working completely.

I debugged the function and the problem is with :

ow_emailRegex.test(ow_urlparamsdecoded)
  1. Why is this error happening?
  2. Is there an alternative to test()? match() did not work either.

Thank you.

Upvotes: 1

Views: 374

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626950

Make the dot or hyphen pattern inside groups obligatory to avoid having consequent +/*-quantifier patterns match the same chars:

\w+(?:[.-]\w+)*@\w+(?:[.-]\w+)*(?:\.\w{2,3})+

See how the regex fails gracefully against your string here.

Note that all [\.-]? are turned to [.-], the whole [.-]\w+ group is still optional as * matches 0 or more occurrences. The dot is not any special inside a character class, that's why I removed the backslash.

Also, you may use non-capturing groups since you are not interested in getting those submatches (and you actually can't in JavaScript).

Upvotes: 2

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