title: Hooking a javascript function to every postback
body: <p>This is some Javascript added on an <code>.aspx</code> page:</p>
  
  <pre><code>&lt;Head&gt;
  &lt;script&gt;
  function SayHello()
  {
      alert('Hello');
  }
  &lt;/script&gt;
  </code></pre>
  
  <p>and here is how I am calling it from code:</p>
  
  <pre><code>protected void Page_Init(object sender, Eventargs e)
  {
      Page.ClientScript.RegisterStartupScript(Page.GetType(),"script","SayHello()",true); 
  }
  </code></pre>
  
  <p>The problem is that the Javascript function is called only one time, on the very first page load. I want it to be called on every post back. for example on every button click</p>