This is kind of annoying when developing javascript inside Visualforce: I can not find my global variables !
Build a Visualforce page with showHeader="false"
<apex:page showHeader="false">
Create a javascript global variable inside the page:
<script> var myVar = 'Hello'; </script>
Save your test page and open it via its URL.
http//[instance].salesforce.com/apex/[pagename]
Now in the browser console (F12 sometimes), type
window.myVar
and return gives you
'Hello'
Now insert this visualforce page as a section in a standard page layout.
Load the standard page and type in the console:
window.myVar
Which returns
undefined
What ?
Where art thou ?