CODEWITHSUNDEEP
javascriptregexpasswords
PHP
PHP

Reputation: 31

password validation using javascript

I need to match a password field using javascript with the following requirements:

  1. Should be alpha numaric with at least one special character.
  2. no spaces to be allowed
  3. should be minimum 10 char and max 20 chars.
  4. No repeate of char more than 2 times.
  5. ~,'.:;^| are not allowed

I have a regex
var password = /^(?=.[0-9])(?=.[!@#$%^&])[a-zA-Z0-9!@#$%^&]{10,20}$/; how can i solve this?

Upvotes: 0

Views: 4545

Answers (4)

Civa
Civa

Reputation: 2176

based on your 5 things in your requirements this is exact pattern you need

^(?=.*[!@#$%^&])(?!.*(.).*\1.*\1)[^\s~,'.:;^|]{10,20}$

Upvotes: 0

Billy Moon
Billy Moon

Reputation: 58531

I would write separate rules (probably using regex for all of them - for consistency - unless performance is a great concern) that each relate directly to a rule on your list.

The code

var pw = "asddfak@kjg";

/* Should be alpha numaric with at least one special character. */
console.log(null !== pw.match(/[@+#$]/));

/* no spaces to be allowed */
console.log(null !== pw.match(/^\S+$/));

/* should be minimum 10 char and max 20 chars. */
console.log(null !== pw.match(/^.{10,20}$/));

/* No repeate of char more than 2 times. */
console.log(null === pw.match(/(.)(.*\1){2}/));

/* ~,'.:;^| are not allowed */
console.log(null !== pw.match(/^[^~,'.:;^|]+$/));

Although it is possible to make the regex more concise, I think it is much more maintainable to make the rules more literal to your intent. If performance is a significant issue (usually not for this kind of thing) then I would avoid regex, and implement the rules using string methods.

Regex Explained

/           // start regex pattern
[           // open character class
@+#$        // match one of these `special` characters
]           // close character class
/           // end regex pattern 

/           // start regex pattern
^           // start matched string
\S+         // one or more (`+`) not spaces (`\S`)
$           // end matched string
/           // end regex pattern 

/           // start regex pattern
^           // start matched string
.{10,20}    // between 10 and 20 of any character (`.`)
$           // end matched string
/           // end regex pattern 

/           // start regex pattern
(.)         // any character captured as group 1
(.*\1){2}   // followed by zero or more of anything (`\.*`) and then the captured group 1 (`\1`) two times (`{2}`)
/           // end regex pattern 

/           // start regex pattern
^           // start matched string
[           // open character class
^~,'.:;^|   // not (`^`) one of these characters
]+          // close character class
$           // end matched string
/           // end regex pattern

p.s. you should keep a lot of comments with regex you use, because unlike books, they are much easier written than read

Upvotes: 1

Loamhoof
Loamhoof

Reputation: 8293

This should work:

/^(?=.*?[!@#$%^&])(?:([a-zA-Z0-9!@#$%^&])(?!.*?\1.*?\1)){10,20}$/

(if by repeat more than 2 times you mean the same character can't appear thrice)

Explanation:
1st condition: at the very beginning, we'll go through the whole string a first time until we find a special character, as soon as we have it, we stop, if we don't, it fails (Source): (?=.*?[!@#$%^&])
2nd condition: nothing to do, [a-zA-Z0-9!@#$%^&] doesn't allow spaces anyway
3rd condition: quantifier: {10,20}
4th condition: the subtle one: as we get through the string, for each character captured, we check the it's not repeated twice more (same source): (?!.*?\1.*?\1)
5th condition: same as whitespaces

Upvotes: 0

Naveed S
Naveed S

Reputation: 5236

This might be the required regex

^(?=.*[!@#$%^&])(?!.*(.).*\1.*\1)[A-Za-z\d!@#$%^&|]{10,20}$

(?=.*[!@#$%^&]) ensures at least one occurrence of the listed characters.

(?!.*(.).*\1.*\1) ensures no character is repeated more than twice.

[A-Za-z\d!@#$%^&|]{10,20} matches 10-20 occurrence of characters from the character class.

Upvotes: 1

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