Change Password Control RegEx validating oddly in IE 7 only

I'm using the Asp.net change password control in my application and all seems to be find and dandy until a user tells me she has a problem meeting the strength requirements when changing her password. Looking into this, she is using IE 7 and no matter what she puts in, the validation fails (and ONLY in IE 7. Firefox, IE 8, Chrome etc. all work as expected). Here is the regex i'm using:

^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*\s).{5,15}$

I've tried out a few others that I've found throughout this site and others that folks seem to be using with no issues and I come across the same problem.

It seems that which ever pattern I enter in last (digit, upper or lower alpha) is the one that is expected to be repeated min of 5 times. For example:

Hello1 (doesn't work)

11111Hello (doesn't work)

Hello11111开发者_如何学C (works)

Again, this is ONLY in IE 7. I've spent too much time on this already and I'm stumped. Anybody have any ideas??

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Apparently Internet Explorer has a bug. Check out this post: A JScript/VBScript Regex Lookahead Bug. The example is the same - a password check - and they provide a work-around. Using their suggested approach as a guide, the pattern becomes:

^(?=.{5,15}$)(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*\s).*

Their pattern is very similar to yours, except for the negative look-around for whitespace.

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Try using .* in the look-arounds. Using just . only covers one character followed by whatever you're specifying in the look-arounds. You want to look all the way ahead and see if anything matches. I tried the following expression in Expresso and it worked with the samples you listed and also failed on invalid inputs as expected.

^(?=.*\d)(?=.*[a-z])(?=.*[A-Z])(?!.*\s).{5,15}$