Regex for allowing alphanumeric,-,_ and space

Character sets will help out a ton here. You want to create a matching set for the characters that you want to validate:

• You can match alphanumeric with a \w, which is the same as [A-Za-z0-9_] in JavaScript (other languages can differ).
• That leaves - and spaces, which can be combined into a matching set such as [\w\- ]. However, you may want to consider using \s instead of just the space character (\s also matches tabs, and other forms of whitespace)
  • Note that I'm escaping - as \- so that the regex engine doesn't confuse it with a character range like A-Z
• Last up, you probably want to ensure that the entire string matches by anchoring the start and end via ^ and $

The full regex you're probably looking for is:

/^[\w\-\s]+$/

(Note that the + indicates that there must be at least one character for it to match; use a * instead, if a zero-length string is also ok)

Finally, http://www.regular-expressions.info/ is an awesome reference

Bonus Points: This regex does not match non-ASCII alphas. Unfortunately, the regex engine in most browsers does not support named character sets, but there are some libraries to help with that.

For languages/platforms that do support named character sets, you can use /^[\p{Letter}\d\_\-\s]+$/

/^[-\w\s]+$/

\w matches letters, digits, and underscores

\s matches spaces, tabs, and line breaks

- matches the hyphen (if you have hyphen in your character set example [a-z], be sure to place the hyphen at the beginning like so [-a-z])

Try this regex:

/^[a-z\d\-_\s]+$/i