title: regular expression to avoid only special chars
body: <p>I'm validating a input text box. I'm new to regexp. I want an expression which throws a validation error if all the characters of input are special characters. but it should allow special characters in the string.</p>
  
  <p>-(**&amp;^&amp;)_) ----> invalid.</p>
  
  <p>abcd-as jasd12 ----> valid.</p>
  
  <p>currently validating for numbers and alphabets with <code>/^[a-zA-Z0-9-]+[a-z A-Z 0-9 -]*$/</code></p>