title: Where to add String prototype
body: <p>I'm currently using JavaScript (CommonJS) in Titanium Studio and have a question about prototyping. 
  Suppose that I want to add a new function to an existing class. For instance: </p>
  
  <pre><code>String.prototype.trim = function() {
      return this.replace(/^\s+|\s+$/g,"");
  }
  </code></pre>
  
  <p>What is the most appropriate place where I should add this code so It became available for all classes right away? </p>
  
  <p>Thanks in advance. </p>