Hello,

I'm doing a 'Visualforce Basics' module and I'm stuck at 'Use Standard Controllers' Unit (link here).
I created a page with the following code:
 

<apex:page>
    <apex:pageBlock title="Account Summary">
        <apex:pageBlockSection>

        </apex:pageBlockSection>
    </apex:pageBlock>
</apex:page>

Then I opened a page via the "Preview" button in a Developer Console and opened a JavaScript console in Chrome where I typed:

$A.get("e.force:navigateToURL").setParams({"url": "/apex/AccSum"}).fire();

And I got the following error:

Uncaught ReferenceError: $A is not defined at <anonymous>:1:1

 

Both the snippets are copied from the Unit's sections, I didn't change anything except the page's name - 'AccSum'. I tried all of the above in a Firefox which also did not work.

Does anyone know what's going on?

Is there a way to retreive it?  It has all the work of the modules, trail, etc that I've completed.  I created another playground but it does not have any accounts.  I'm not able to compete a module because it has not accounts for me to access.  Any help would be appreciated!  Thanks.