title: Iterate over a collection of objects in javascript and return true from that function
body: <p>I have an object called collection, and I want to test to see if justin is part of this collection.</p>
  
  <pre><code>collection = { 0:{screen_name:"justin"},1:{screen_name:"barry"}}
  </code></pre>
  
  <p>I'm trying to discover the most efficient method, to pass in a name to function called <code>present_user(user)</code>, to see if the user is part of the collection and I'm kind of stumped. </p>
  
  <p>So my collection is built up of objects 0, 1, n+1. I'm trying to iterate through this collection. So far I only test [0]</p>
  
  <pre><code>function present_user(user) {
    collection[0]["screen_name"] == user -&gt; return true in the case of "justin"
  }
  </code></pre>
  
  <p>How can I iterate over all values of this collection, and return true if the user_name "justin" is passed into a function?</p>