title: Determine whether a string is "empty"
body: <p>I need a JavaScript function to tell me whether a string object is empty. By "empty", I mean that it's not all just whitespace characters. I've written this prototype:</p>
  
  <pre><code>String.prototype.isEmpty = function() {
    return this.length === 0 || this === " " || this.test(/^\s*$/);
  }
  </code></pre>
  
  <p>Is this alright?</p>
  
  <p>Is there a more-performant version of this out there?</p>