directly paste Code :
<HTML xmlns = "http://www.w3.org/1999/xhtml"> <br/> <pead runat = "server"> <br/> <title> comboxtest </title> <br/> <link href = "ext-all.css" mce_href = "ext-all.css" rel = "stylesheet" type = "text/CSS"/> </P> <p> <MCE: script src = "ext-base-debug.js" mce_src = "ext-base-debug.js" type = "text/JavaScript"> </MCE: SCRIPT> </P> <p> <MCE: script src = "ext-all-debug.js" mce_src = "ext-all-debug.js" type = "text/JavaScript"> </MCE: SC Ript> </P> <p> <MCE: script src = "jquery. JS "mce_src =" jquery. JS "type =" text/JavaScript "> </MCE: SCRIPT> </P> <p> </pead> <br/> <body> <br/> <Form ID = "form1" runat = "server"> <br/> <div> <br/> <input id = "ddlcombox" type = "text"/> <br/> <input type = "button" id = "btncheck" onclick = "selectcheck () "value =" get drop-down box value "/> <br/> </div> <br/> </form> <br/> </body> <br/> </ptml> </P> <p> <MCE: script Type = "text/JavaScript"> <! -- <Br/> $ (function () {<br/> bindselect ("ddlcombox"); <br/>}); <br/> function bindselect (objid) {<br/> var combox = new Ext. form. comboBox ({<br/> selectonfocus: True, <br/> displayfield: 'desc', <br/> valuefield: 'id', <br/> store: New Ext. data. jsonstore ({<br/> data: [{"ID": "", "DESC": "[not set]" },{ "ID": "2010 ", "DESC": "inspection" },{ "ID": "2011", "DESC": "training"}], <br/> fields: [{"name ": "ID", "type": "string" },{ "name": "DESC", "type": "string"}], <br/> prunemodifiedrecords: true}), <br/> typeahead: True, <br/> mode: 'local', <br/> triggeraction: 'all', <br/> lazyrender: True, <br/> applyto: objid, <br/> hiddenname: 'selectid' <br/> }); </P> <p >}</P> <p> function selectcheck () {<br/> var Vals = $ ("# selectid") [0]. value; <br/> var texts =$ ("# ddlcombox "). val (); <br/> alert (texts); <br/> alert (Vals); <br/>}< br/> // --> </MCE: SCRIPT>