Validating input using regular expression in Javascript

Question

I need to validate text box, it should accept only alphabets (capital or small), digits, and .,?-_. It should not accept any other values. It should not accept same value like ...... or ,,,,, or ----- or ???? or _____. It should not accept values like ,._ it should contain either alphabet or digit with this, like eg _.ab.?.

Can you describe what the field represents? That would make it clearer what logic you are trying to capture. — Michael Aaron Safyan
– Michael Aaron Safyan, Commented Feb 25, 2011 at 9:56
Please show some specific code you've tried. If you don't know where to start, google "javascript regex tutorial" — Matt
– Matt, Commented Feb 25, 2011 at 9:57
Related to you question, I hope you know that you in any case also MUST do the same input validation server side as well, no matter how perfect your javascript is doing it. — hlovdal
– hlovdal, Commented Feb 25, 2011 at 12:38

Tim Pietzcker · Accepted Answer · 2011-02-25 10:18:07Z

2

So you want the string to contain at least one (ASCII) alphanumeric character and at least two different characters?

Try

/^(?=.*[A-Z0-9])(?!(.)\1*$)[A-Z0-9.,?_-]*$/i

Explanation:

^                # start of string
(?=.*[A-Z0-9])   # assert that there is at least one of A-Z or 0-9
(?!(.)\1*$)      # assert that the string doesn't consist of identical characters
[A-Z0-9.,?_-]*   # match only allowed characters
$                # until the end of the string

edited Feb 25, 2011 at 10:18

answered Feb 25, 2011 at 10:00

Tim Pietzcker

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