How to convert this document.getElementById("<%=myvar1.ClientID%>"); into jquery

How to convert this document.getElementById("<%=myvar1.ClientID%>"); into jquery

Hi everyone,
 
I'm newbie in jquery. Now i want to convert this javascript to jquery
var  abc = document.getElementById( "<%=myvar1.ClientID%>" );
 
how can i do?
Any idea?
 
Thanks in advance,
Nasri