Q:

Get javascript variable in an iframe from parent window in a different domain

I have an iframe in a domain "someplace.com" being loaded into "anotherplace.com" 's window.
Old questions say you can't access variables across domains: Sharing global javascript variable of a page with an iframe within that page
But now that we have CORS, I'm wondering if this is possible. Are we now able to access JS variables in an iframe's parent if we enable CORS between the domains?

A:

You need to use the Web Messaging API.
https://developer.mozilla.org/en-US/docs/Web/API/Window.postMessage

