HTML5 Pattern Regex Password Match

Question

Looking for some help for validating password with the following rules:

8+ characters

contains at least 1 upper case letter

contains at least 1 lower case letter

contains at least 1 number

Cannot start with a number

contains no special characters

I had gotten as far as:

(?=.*\d.*)(?=.*[a-z].*)(?=.*[A-Z].*)(?=.*[!#\$%&\?].*).{8,}

but can't seem to figure out how to get the first digit to not match a digit, and set the special character class to not match as well. Any help would be greatly appreciated.

just a remark, for beter password safety, it may be good to allow some special characters though, to make the spectrum of possibilities the widest possible — Laurent S.
– Laurent S., Commented Jun 7, 2013 at 13:45

pete · Accepted Answer · 2013-06-07 14:00:41Z

4

I find that breaking this down into individual tests is:

easier to code
easier to read
easier to maintain
and more flexible when requirements change

Try something like this:

var testPassword = function (password) {
    var minLengthMet = password.length >= 8,
        hasUpper = (/[A-Z]+/).test(password),
        hasLower = (/[a-z]+/).test(password),
        hasNumber = (/[0-9]+/).test(password),
        letterBegin = (/^[A-Za-z]/).test(password),
        noSpecials = !(/[^A-Za-z0-9]+/).test(password);
    return minLengthMet && hasUpper && hasLower && hasNumber && letterBegin && noSpecials;
};

See it in action here: http://jsfiddle.net/H9twa/

answered Jun 7, 2013 at 14:00

pete

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3 Comments

Jan Turoň Over a year ago

great idea! just notes: [A-Za-z] is the same as \w, [0-9] is the same as \d, [^A-Za-z0-9] could be [^\w\d]

Pierluc SS Over a year ago

@JanTuroň, that's not 100% true Jan. \w also includes underscores. \w would be the same as [A-Za-z0-9_]

pete Over a year ago

@JanTuroň: They are not the same. \w is the same as [A-Za-z0-9_]. You are correct about \d. Personally I prefer the character classes over the shorthand as I find them easier to read.

user1919238 · Accepted Answer · 2013-06-07 13:45:36Z

3

Here is what I would go with:

(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*[!#\$%&\?])^\D.{7}

Note that the .* after each look-ahead term was superfluous.

(?!...) is a negative look-ahead, to make sure there are no special characters.

^\D requires that the first character be a non-digit. Then I simply require 7 characters after that, because the end is not enforced.

But why exclude special characters from passwords? Usually just the opposite is encouraged.

answered Jun 7, 2013 at 13:45

user1919238

2 Comments

Matthew Gilliard Over a year ago

As much as I admire the mastery of complex regexes, if I found something like this in the code I am working on I would seek out the author and send them a strongly-worded letter of complaint.

user1919238 Over a year ago

@MatthewGilliard, point taken. It is often better to break it into multiple steps. However, I don't think this one is really that complex if the code base uses a lot of regexes and everyone is familiar with them (and it is well-documented with a comment).

Matthew Gilliard · Accepted Answer · 2013-06-07 14:00:34Z

3

How about:

pwd.length >= 8 &&
pwd.match(/[A-Z]/) &&
pwd.match(/[a-z]/) &&
pwd.match(/\d/) &&
!pwd.match(/^\d/) &&
!pwd.match(/[!#\$%&\?]/);

Just in case you need to maintain this code ever?

answered Jun 7, 2013 at 14:00

Matthew Gilliard

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1 Comment

GillesC Over a year ago

Hardly any easier to maintain and takes more time to run. The regex solution is dead simple and if people don't understand regex then they still won't get what the values passed to the match method are anyway. I know good clean code is important but dumbing syntax for people who don't understand it seems overkill. Like writing a book in English so it can be read by the French.

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