What would be the best way to check that a javascript string is at least four characters long, contains at least one lowercase letter, one uppercase letter and a digit?
3
- 4Sharing some code would be the best way, I guess...Hiren Pandya– Hiren Pandya2013-04-18 11:14:53 +00:00Commented Apr 18, 2013 at 11:14
- Regular expressions, I guess..user447356– user4473562013-04-18 11:15:17 +00:00Commented Apr 18, 2013 at 11:15
- What methods have you tried already? What problems did you face?Lix– Lix2013-04-18 11:16:09 +00:00Commented Apr 18, 2013 at 11:16
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3 Answers
Testing for lowercase letters has already been covered elsewhere:
function hasLowerCase(str) { return (/[a-z]/.test(str)); } It's trivial to modify that to implement hasUpperCase and hasDigits.
Once you have written these functions, you can just check that:
if( hasLowerCase(passwd) && hasUpperCase(passwd) && hasDigits(passwd) ) { // Its a valid password! } If you use it in many places, consider making a new function:
function isPasswordValid(str) { return hasLowerCase(passwd) && hasUpperCase(passwd) && hasDigits(passwd); } Which you can further use like:
if( isPasswordValid("passwd") ) { // ... } 
5 Comments
user1334130
I already looked at regular expressions and that example but am not too familiar with regex. Would it possible to have one regex statement or would I need three statements - one for the lower, upper and digit cases, then check that all three are true?
jsalonen
Yes you can do exactly that!
user1334130
OK so I'll need a check for all three.
ColBeseder
Testing for all three in one regex is not a good idea because you don't know what order they're in.
jsalonen
Wow stop! I definitely meant using THREE regexes just for this exactly same reason! Sorry for ambiguity!
Here's a quick validation function:
function validate(str) { return str.length > 3 && /[a-z]/.test(str) && /[A-Z]/.test(str) && /[0-9]/.test(str) ; } It checks the length and then runs regular expressions looking for lowercase, uppercase and numbers (in that order). If all are true (length > 3 and has lowercase and has uppercase and has a number) it returns true. Otherwise, it returns false.
use it like this:
validate("aaaa") // returns false validate("aA1") // returns false validate("aA12") // returns true Comments
I wrote a function, same like ColBeseder .added a type checking string
function check( str ){ return ( typeof str == 'string') && ( str.length >= 4 ) && /[a-z]/.test( str ) && /[A-Z]/.test( str ) && /[0-9]/.test( str ) } and call its as check('AAA1a') , which returns a boolean
