How do I get the row number back from my PageBlockTable with javascript or jQuery? I’ve tried a few methods, but they always return [object Object].

I am displaying repeating elements in a PageBlockTable. When I change the contents of Field1, I want to perform a calculation in my controller, and place the cursor in Field2.

Yes, I know the scripting looks like I'm lost - I am. 

<apex:page controller="TestTabbingController" id="PageId">

<apex:includeScript value="{!URLFOR($Resource.jQuery, '/js/jquery-1.8.2.min.js')}"  />
<apex:includeScript value="{!URLFOR($Resource.jQuery, '/js/jquery-ui-1.8.24.custom.min.js')}"  />
<apex:stylesheet value="{!URLFOR($Resource.jQuery, '/css/ui-lightness/jquery-ui-1.8.24.custom.css')}"  />


<script type="text/javascript">
	  j$ = jQuery.noConflict();
	  
	  function putErThereDude()
	  {
	  
         var myRow = j$('[id*=PageBlockTableId]');
		 alert("myRow is " + myRow) ; 
			   
	     var Part1 = "PageId:FormId:PageBlockId:PageBlockSectionId:PageBlockTableId:";
		 var myRow = j$('[id*=PageBlockTableId]');
		 var Part3 = ":Field2" ; 
		   
		 var PutIt = Part1 + myRow + Part3; 
		 alert("PutIt is " + PutIt) ; 
		   
		 var myElement = document.getElementById(PutIt);
         alert("myElement is " + myElement) ; 
           
         j$(myElement).focus();		   
	  
	  }


</script>

   <apex:form id="FormId">
      
      
      <apex:PageBlock title="Confirmation" id="PageBlockId">  
     
      
         <apex:PageBlockSection title="GPS Print Products" id="PageBlockSectionId" columns="1" >

               
               <apex:pageBlockTable value="{!OpportunitiesWithIndex}" var="oppWrapped" style="width:100%" id="PageBlockTableId">
               
                
                    <apex:column headerValue="Name" Id="GPSD_Name">
                        <apex:outputLabel value="{!oppWrapped.opp.name}"                 id="Name" >     
                        </apex:outputLabel>                        
                    </apex:column>

                    <apex:column headerValue="Field 1" Id="GPSD_Field1">
                        <apex:inputField value="{!oppWrapped.opp.X_Field_1__c}"          id="Field1" >
                            
                            <apex:actionSupport event="onchange" action="{!doSomething}" reRender="PageBlockSectionId" oncomplete="putErThereDude(event.target.focus())" />
                        </apex:inputField>                           
                    </apex:column>     


                    <apex:column headerValue="Field 2" Id="GPSD_Field2">
                        <apex:inputField value="{!oppWrapped.opp.X_Field_2__c}"          id="Field2" >     
                           <apex:actionSupport event="onchange" action="{!doSomething}" reRender="PageBlockSectionId" />   
                        </apex:inputField>                         
                    </apex:column>

                    <apex:column headerValue="Field 3" Id="GPSD_Field3">
                        <apex:inputField value="{!oppWrapped.opp.X_Field_3__c}"          id="Field3" >     
                           <apex:actionSupport event="onchange" action="{!doSomething}" reRender="PageBlockSectionId" />     
                        </apex:inputField>                         
                    </apex:column>

                    
                    <apex:column headerValue="Field 4" Id="GPSD_Field4">
                        <apex:inputField value="{!oppWrapped.opp.X_Field_4__c}"          id="Field4" >       
                           
                        </apex:inputField>                         
                    </apex:column>
                    
               
                
                
                </apex:pageBlockTable>
                
                


         </apex:PageBlockSection>
        
      </apex:PageBlock>
      
 
   </apex:form>
</apex:page>