title: How to get UniqueID from document.getElementById()?
body: <p>I want to use __doPostBack javascript function.<br></p>
  
  <pre><code>__doPostBack(obj.UniqueID,'');
  </code></pre>
  
  <p>But I only know ClientID of my object  -<br></p>
  
  <pre><code>ctl00_cpholder_myObjId 
  document.getElementById("ctl00_cpholder_myObjId").id //This will get ctl00_cpholder_myObjId,but UniqueID is ctl00$cpholder$myObjId
  </code></pre>
  
  <p>How can I get UniqueID for PostBack?
  Can I simply replace '_' with '$'?<br>
  Thank u.</p>