 <p>Try <strong>Event Delegation</strong>:</p> <pre><code>$(document).on("change", "#Sites", function(){ var siteId = this.value; GetSectors(siteId); }); </code></pre> <blockquote> <p>The bubbling behavior of events allows us to do "event delegation" — <strong>binding handlers to high-level elements, and then detecting which low-level element initiated the event.</strong></p> <p>Event delegation has two main benefits. <strong>First</strong>, it allows us to <strong>bind fewer event handlers</strong> than we'd have to bind if we were listening to clicks on individual elements, which can be <strong>a big performance gain</strong>. <strong>Second</strong>, it allows us to <strong>bind to parent elements</strong> — such as an unordered list — and know that our event handlers will <strong>fire as expected even if the contents of that parent element change.</strong></p> </blockquote> <p>Taken from: <a href="http://jqfundamentals.com/chapter/events">http://jqfundamentals.com/chapter/events</a></p> <blockquote> <p>Delegated events have the advantage that <strong>they can process events from descendant elements that are added to the document at a later time. By picking an element that is guaranteed to be present at the time the delegated event handler is attached, you can use delegated events to avoid the need to frequently attach and remove event handlers.</strong> This element could be the container element of a view in a Model-View-Controller design, for example, or document if the event handler wants to monitor all bubbling events in the document. The document element is available in the head of the document before loading any other HTML, <strong>so it is safe to attach events there without waiting for the document to be ready.</strong></p> </blockquote> <p>Taken from: <a href="http://api.jquery.com/on/">http://api.jquery.com/on/</a></p>