How to use regex to check that user input does not consist of special characters only?

Question

How to put a validation over a field which wouldn't allow only special characters, that means AB#,A89@,@#ASD is allowed but @#$^& or # is not allowed. I need the RegEx for this validation.

Answer 1

str.match(/^[A-Z#@,]+$/)

will match a string that...

• ... starts ^ and ends $ with the enclosed pattern
• ... contains any upper case letters A-Z (will not match lower case letters)
• ... contains only the special chars #, @, and ,
• ... has at least 1 character (no empty string)

For case insensitive, you can add i at the end : (i.g. /pattern/i)

** UPDATE **

If you need to validate if the field contains only specials characters, you can check if the string contains only characters that are not words or numbers :

if (str.match(/^[^A-Z0-9]*$/i)) {
   alert('Invalid');
} else {
   alert('Valid');
}

This will match a string which contains only non-alphanumeric characters. An empty string will also yield invalid. Replace * with + to allow empty strings to be valid.

Answer 2

If you can use a "negative match" for your validation, i. e. the input is OK if the regex does not match, then I suggest

^\W*$

This will match a string that consists only of non-word characters (or the empty string).

If you need a positive match, then use

^\W*\w.*$

This will match if there is at least one alphanumeric character in the string.