RegEx for Javascript to allow only alphanumeric

Question

I need to find a reg ex that only allows alphanumeric. So far, everyone I try only works if the string is alphanumeric, meaning contains both a letter and a number. I just want one what would allow either and not require both.

Thanks!

Answer 1

^\s*([0-9a-zA-Z]*)\s*$

or, if you want a minimum of one character:

^\s*([0-9a-zA-Z]+)\s*$

Square brackets indicate a set of characters. ^ is start of input. $ is end of input (or newline, depending on your options). \s is whitespace.

The whitespace before and after is optional.

The parentheses are the grouping operator to allow you to extract the information you want.

EDIT: removed my erroneous use of the \w character set.

Answer 2

/^[a-z0-9]+$/i

^         start of string
[a-z0-9]  a or b or c or ... z or 0 or 1 or ... 9
+         one or more times (change to * to allow empty string
$         end of string

/i        case-insensitive

Answer 3

Use the character class. The following is equilavent to a "^[a-zA-Z0-9]+$":

^\w+$

Explanation:

• ^ start
• \w any work character (A-Z, a-z, 0-9).
• $ end

Edit: \w matches one additional character, the underscore.