javascript getElementById gives error in chrome but works fine in IE -

here javascript function :

function deletealert(tabstate){     var form = window.document.alertsform;     var numofelements = form.elements.length;     var okdelete = "false";     (i=0; < numofelements; i++)     {         if(form.elements[i].checked)         {             okdelete = "true";             break;         }else{             okdelete = "false";          }      }     if(okdelete == "true")     {         //changpage("screen1b.html");  prototype         form.action="/cpi/producer/myalerts/alertsgateway?jadeaction=ma06&tab="+tabstate;         form.document.getelementbyid('deletealertsbutton').disabled=true;         form.submit();      }else{         alert("please select 1 or more items delete.");     } } 

i 'm calling function in 2 jsps , code snippet same both (note same id values)

<input type=button value="delete" id="deletealertsbutton" title="delete" class=fbutton onclick="javascript:deletealert('<%=state %>');"> 

now works perfect both jsp in ie8 in chrome , gives error second jsp : uncaught typeerror: cannot read property 'getelementbyid' of undefined

please help.

your reference form.document incorrect. "document" outside form

so change:

form.document.getelementbyid('deletealertsbutton').disabled=true; 

to

document.getelementbyid('deletealertsbutton').disabled=true;