Sequence repeat validation using Regular expression in javascript

Question

Iam pretty new to regular expressions .I would like to prevent the user from entering in

String data using javascript function with the following condition .

Same sequence of characters cannot be repeated two or more times

  aabhi - is allowed 
 aabbcc -  is allowed

 dayday - not allowed
 abab - not allowed
 ababab - not allowed 
 aaaa - not allowed

this applies to numbers too .Can someone help me with this ? Thanks in advance

well thats the requirement ;) since its 'sequence' and not characters that they have mentioned in condition , i guess that single character is allowed two times ..thanks for asking out .. — Muthu Raman
– Muthu Raman, Commented Dec 4, 2013 at 16:43
am sorry ..Typo error .edited the question now aaaa not allowed — Muthu Raman
– Muthu Raman, Commented Dec 4, 2013 at 16:48

anubhava · Accepted Answer · 2013-12-04 17:08:08Z

3

Based on your inputs you can use this regex:

 /(\w{2,})(\1)/

Code:

re = /(\w{2,})(\1)/;

s = 'dayday';
if (re.test(s))
   console.log("invalid);
else
   console.log("valid);

answered Dec 4, 2013 at 16:47

anubhava

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2 Comments

It worked ! you made my day:) .Being new , could you suggest me best place to know or have a trial with regular expressions ?thanks once again

You're most welcome. Best reference for regex is: regular-expressions.info