title: Best practice for testing return value of indexOf
body: <p>What do you normally write when you're testing for the return value of indexOf?</p>
  
  <pre><code>if str.indexOf("a") &lt; 0 
  </code></pre>
  
  <p>vs</p>
  
  <pre><code>if str.indexOf("a") == -1
  </code></pre>
  
  <p>Would one method be preferred over the other?</p>
  
  <p>I'm actually posing this question for any function in any language that returns -1 on error.</p>
  
  <p>I normally prefer the &lt; 0 approach, because if the function is extended to return -2 on some other case, the code would still work.</p>
  
  <p>However, I notice that the == -1 approach is more commonly used. Is there a reason why?</p>