title: How to check for alphanumeric characters
body: <p>I'm writing a custom method for a jQuery plugin:</p>
  
  <pre><code>jQuery.validator.addMethod("alphanumeric", function(value, element) {
          return this.optional(element) || (/*contains "^[a-zA-Z0-9]*$"*/);
  });
  </code></pre>
  
  <p>I know the regexp for what I want, but I'm not sure how to write something in JS that will evaluate to True if it contains the alphanumeric characters. Any help?</p>