I want a regex pattern allowing only alphanumeric value, neither only alphabets nor digits, having minimum length = 4 and maximum length = 15,
I tried using /^[a-zA-Z0-9]{4,15}$/ , but this pattern also allows only alphabets and only digits.
Please help me out
This should do the trick:
^(?=^.{4,15}$)([a-zA-Z]+[0-9][a-zA-Z0-9]*|[0-9]+[a-zA-Z][a-zA-Z0-9]*)$
See working example here: http://regexr.com?351ia
Explanation: (Updated: now with length check)
First the positive lookahead (?=^.{4,15}$) checks the length of your string.
If your string starts with a letter this part of the regex is used to evaluate it:
[a-zA-Z]+[0-9][a-zA-Z0-9]*
[a-zA-Z]+ means that the string starts with at least one letter[0-9] then at some point there must be a number[a-zA-Z0-9]* followed by any amount of numbers or lettersIf your string starts with a number the second part of the regex is used:
[0-9]+[a-zA-Z][a-zA-Z0-9]*
Same as the above, only this time there must be a letter somewhere in the string.
You may want to do a double lookahead to look for numbers and letters, once numbers and letters are found, the match will continue, else it won't.
Regex: /^(?=.*?[a-zA-Z])(?=.*?[0-9])[a-zA-Z0-9]{4,15}$/
Use your original for the alphanumeric and length tests, then verify that the string contains alpha and numeric by testing for a digit followed by an alpha or vice-versa anywhere in the string.
/^[a-z\d]{4,15}$/i.test (s) && /\d[a-z]|[a-z]\d/i.test (s);
