[SalesForce] How to pass a variable’s value of child visualforce page to a variable in parent visualforce using js

I am new to salesforce and I am doing a task to create a new Company by using visualforce page. From visualforce page, I am using <apex:outputLink> to open a popup window with a url like 'apex/page1'. This page has a standard controller that is something like :

<apex:page standardController="Company__c" showHeader="true" sidebar="true">

By clicking outputLink, we got a popupwindow that is on back-end a visualforce page which has a custom controller (apex class) named apexClass1.

From this custom controller, I am using PageReference to make a reference to a page something like :

'/apex/page2?c='+code+'&recordId='+recordId)

This page2 has its own custom controller named as "apexClass2".

Now My problem is that from this apexClass2 class, I want value of a variable to use it into the first page's js portion that is opening a popup window.

How can I do that? Is it possible in salesforce?

Please help.

Now I am posting my code so that you can easily my problem…

<<——–1st Page to create a company——->>

var myOpenWindow = function(URL) {
var myOpenedWindow = myOpenedWindow || window.open(URL,'window.childWin','height=600,width=600,left=100,top=100,scrollbars=yes,toolbar=no,status=no');;
myOpenedWindow.location.href= URL;
myOpenedWindow.focus();

            window.intervalId = window.setInterval('window.checkIfChildWindowIsClosed()',1*1000);

            // Here value should retrieve...
             var recID = "How to get Value from 3rd page here"; 

            //add check function to window
            window.checkIfChildWindowIsClosed = function()
            {
                if(myOpenedWindow.closed)
                {
                    window.clearInterval(window.intervalId);
                    window.parent.location.href = 'https://na11.salesforce.com/'+recID;
                }
            }
        }

</script>

Search

Now <<———- Page 2 ————–>>

Enter Name:

            <apex:column value="{!d.name}" headerValue="Name"/>
            <apex:column headerValue="Select">
                <apex:commandButton action="{!QDetail}" value="Go" rerender="hiddenBlock">
                    <apex:param name="code" value="{!d.Code}" assignTo="{!code}"/>
                </apex:commandButton>
            </apex:column>
        </apex:pageBlockTable>
    </apex:pageBlock>
    <apex:pageBlock id="hiddenBlock" rendered="false"></apex:pageBlock>

</apex:form>

<<—— Controller of Page 1 is ——->>

public class QuandlCntl {
public string searchQuery {get; set;}
public string updateQuery {get; set;}
public string qAPIKey {get; set;}

public List<SearchedDocs> listDocs{get;set;}

public String code {
    get;
    // *** setter is NOT being called ***
    set {
        code = value;
        //System.debug('value: '+value);
    }
}


public QuandlCntl(){
QuandleConnect QuandleCon = new QuandleConnect();
    qAPIKey = QuandleCon.QuandleAPIKey;
    searchQuery = ApexPages.CurrentPage().getparameters().get('cname');
}

// @RemoteAction
public void SearchQuandl(){
System.debug(searchQuery);
try{
httpReq(searchQuery.replace(' ', '+'));
}
catch(System.Exception e){
ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.ERROR, 'Quandle Search Data Failed: please retry'));
}
}

public PageReference QDetail(){

    integer underScore = code.indexOf('_');

    code = code.substring(underScore+1);
    string recordId = ApexPages.CurrentPage().getparameters().get('recordId');
    PageReference pr = new PageReference('/apex/QuandleStockDetailsVfp?c=' + code+'&recordId='+recordId);
    return pr;
}

}

You can see that from method QDetails, I am referencing to a page that is:

                           <<---- Page 3---->> 

.inlineTables{
display: inline-block;
}

            function ClosePopup()
            {
                console.log('Call close popup');

                var recordId = '{!recordId}';  
                var resp = '{!message}';

                alert(rest);
                if(resp == 'success'){
                    setTimeout(function(){ 
                        window.parent.close();
                    }, 100);
                }
            }
        </script>  
    </apex:outputPanel>

<<———- controller for this page is ————–>>
public class QuandlStockDetailsCntl {

public string recordId{get;set;}
public String message {get;set;}




public QuandlStockDetailsCntl(){
    QuandleConnect QuandleCon = new QuandleConnect();
    qAPIKey = QuandleCon.QuandleAPIKey;
    recordId = queryString('recordId');  // This the variable whose value I need on page 1
}

public PageReference saveQuandleData(){
System.debug('record Id:'+ recordId);
List MasterListValues = new List();
List Company;
Company__c companyObj;
//if(recordId == null){
ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.CONFIRM, 'Successfully saved data in CRM.'));
// }

    Company = [select Address__c, Annual_Revenue__c, Cash_Equivalents__c from Company__c where Id = :recordId];                        

    if(Company.isEmpty()){
        Company__c compny = new Company__c();


        insert compny;
        recordId = compny.Id;  // here value of recordId is changed that is the required value in page 1...

        ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.CONFIRM, 'Successfully saved data in CRM.')); 
        PageReference pr = new PageReference('/apex/QuandleSuccessRecVF');
        return pr;
    }

}

This is the full scenario. From 3rd apex class, value of variable "recordId" is needed in 1st page…

Any help will be appreciated!