title: battery-friendly way to detect if a textbox's content has changed
body: <p><a href="https://stackoverflow.com/questions/1481152/jquery-how-to-detect-a-textboxs-content-has-changed%20discusses">This question's answers</a> propose using <code>window.setInterval</code> as the only reliable way to immediately detect (without waiting for blur) if a text box's content is changed, given that some textbox changes can happen via events other than key presses. </p>
  
  <p>Even on my desktop PC I see IE or Firefox chewing up a non-trivial percentage of CPU with a 500 msec setInterval running with a relatively simple handler checking a few textboxes. This is OK on a desktop PC but on laptops and mobiles it will hurt battery life. </p>
  
  <p>What's a good way using jquery to minimize CPU utilization but still provide fast updates in response to changes (including clipboard pasting, ajax updates, etc. not just key presses) to a textbox? </p>