Angular reactive forms pattern validator adding $ to regex and breaking validation

Question

I'm trying to validate a password with the following regex:
^(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.{8,}).
Note that there is no terminating $ char, because that would prevent valid passwords from being accepted. (I'm not sure why the input field doesn't terminate the string).
However, Angular's Validators.pattern adds the end of string char. And therefore my valid passwords fail.
How do I prevent the pattern validator from adding the $?
I suppose I could roll my own password validator, but surely there is a better solution...?

EDIT: Passwords that should succeed:

• Test1234
• tEst1234
• tesT1234
• 1234Test
• 1234tesT
• t#St1234

Passwords that should fail:

• TEST1234
• test1234
• tEst123
• Test123
• testtest
• 12345678

Validator declaration:

this.password = new FormControl('', [Validators.required, Validators.pattern('^(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.{8,})')]);
this.userForm.addControl('Password', this.password);

Solution

You may add a .* at the end, or even revamp the pattern a bit to convert one lookahead into a consuming pattern:

Validators.pattern('(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9]).{8,}')

Or, better, when using a regex for password validation, follow the principle of contrast:

Validators.pattern('(?=[^A-Z]*[A-Z])(?=[^a-z]*[a-z])(?=[^0-9]*[0-9]).{8,}')

Angular will add ^ and $ on both ends of the regex pattern, so the pattern will look like

^(?=[^A-Z]*[A-Z])(?=[^a-z]*[a-z])(?=[^0-9]*[0-9]).{8,}$

Note it won't add the anchors automatically if you use a regex literal, add them manually:

Validators.pattern(/^(?=[^A-Z]*[A-Z])(?=[^a-z]*[a-z])(?=\D*\d).{8,}$/)

With a regex literal, you may use single backslashes in regex escapes (/\d/ to match a digit vs. "\\d" in a string literal).

See the regex demo

Details

• ^ - start of string
• (?=[^A-Z]*[A-Z]) - at least 1 uppercase ASCII letter
• (?=[^a-z]*[a-z]) - at least 1 lowercase ASCII letter
• (?=[^0-9]*[0-9]) - at least 1 ASCII digit
• .{8,} - any 8 or more chars (other than line break chars)
• $ - end of string.

Comments

[AvailableName]

Changing the length lookahead to a consuming pattern solved it. Thanks.

[Jignesh Mistry]

Can i assign this dynamically i mean (?=[^A-Z]*[A-Z]) this code validates for 1 upper case letter what if i want 2 uppercase letters ?

[Wiktor Stribiżew]

@JigneshMistry Replace (?=[^A-Z]*[A-Z]) with (?=(?:[^A-Z]*[A-Z]){2})

[Jignesh Mistry]

Thanks buddy it worked :) Just one more trouble can u send the regex for 2 Numeric & 2 special characters ?

[Wiktor Stribiżew]

@JigneshMistry They are formed the same way as above.

[Jignesh Mistry]

regex for special characters is not mentioned above

[Wiktor Stribiżew]

@JigneshMistry What chars do you consider special? Anyway, still, it will be formed the same way: (?=(?:[^special_chars]*[special_chars]){2})

[Jignesh Mistry]

! @ # $ % ^ & * ( ) - all these i am considering as special characters

[Wiktor Stribiżew]

@JigneshMistry So, I guess there is no problem with that. (?=(?:[^!@#$%^&*()]*[!@#$%^&*()]){2})

[Jignesh Mistry]

Angular is throwing this error after puting special characters ERROR SyntaxError: Invalid regular expression: /^(?=(?:[^!@#$%^&*()]*[!@#$%^&*()]){2})(?=(?:[^A-Z]*[A-Z]){1‌​})(?:[^!-0]*[!-0]){2‌​})(?=(?:[^0-9]*[0-9]‌​){1}).{8,}$/: Unmatched ')'

[Wiktor Stribiżew]

@JigneshMistry Your pattern is corrupt. I think you wanted to write it as /^(?=(?:[^!@#$%^&*()]*[!@#$%^&*()]){2})(?=[^A-Z]*[A-Z])(?=(?‌​:[^!-0]*[!-0]){2})(?‌​=[^0-9]*[0-9]).{8,}$‌​/