I am to validate against following conditions:
I used
/^\d*[a-zA-Z][a-zA-Z0-9]+/
It is working fine for all scenario but it does expect 2 characters or numbers or combination of two before entering special character.
Examples:
a!!@#$*()_ fails but should pass
a1!@#$*()_ passes
Please help correcting the regex.
tl;dnr answer:
/^(?=[!-~]+$)(?=.*[a-zA-Z0-9])/
Explanation:
A common way to express "AND" conditions in regular expressions is like the following:
/
^
(?= pattern 1)
(?= pattern 2)
(?= pattern 3)
etc
/
Basically, we accept the start of input (^) only if the rest matches all given patterns. Otherwise, the whole expression fails.
In your example, the pattern 1 is to match everything, including "special characters". From your comment, you're looking for the printable ASCII range. An ASCII char is [!-~] and since we don't want anything else (like "international chars") and don't allow empty strings, the final pattern is:
[!-~]+$
The second pattern is "at least one alphanumeric", which can be rephrased as "any amount of anything else, then one digit or letter", that is,
.*[A-Za-z0-9]
Putting it all together:
/^(?=[!-~]+$)(?=.*[a-zA-Z0-9])/
Some testing:
re = /^(?=[!-~]+$)(?=.*[a-zA-Z0-9])/
console.log(re.test("hi")) // true
console.log(re.test("a!!@#$*()_")) // true
console.log(re.test("~!!@#$*()_")) // false
console.log(re.test("π+1")) // false
console.log(re.test("")) // false
Seems to work!
Your regex requires an alphabet character followed by an alphanumeric character. Clearly the first example fails that condition, while the second passes.
Your conditions have huge overlap, also. Saying it must contain "at least one alphabet or alphanumeric character" is the same as saying simply it must contain "at least one alphanumeric character". This condition also precludes the need to say the string cannot all be special characters; although there, you may have just been clarifying. The regex you need is very simple:
/[a-zA-Z0-9]/.test(str)
It searches anywhere in str for an alphanumeric character.
^ or $ binding the match to the start or end of the string. Therefore, all other characters are ignored. The only thing that matters is that somewhere in the string, there is an alphanumeric character.^(?=.*[a-zA-Z0-9])[a-zA-Z0-9!@#$%^&*]+$, but I truly think that you should try to understand the original regex provided before blindly going with this on (just because it might look more like what you're expecting)./[a-zA-Z0-9]/Your regex:
/[a-zA-Z0-9]/.test(string)
[Edit] this is actually the same answer as @acheong87...
\w.
[^\W_] ;)
[a-zA-Z][a-zA-Z0-9]+.π"special"?