dart:html

parent property

WindowBase parent

A reference to the parent of this window.

If this WindowBase has no parent, parent will return a reference to the WindowBase itself.

IFrameElement myIFrame = new IFrameElement();
window.document.body.elements.add(myIFrame);
print(myIframe.contentWindow.parent == window) // 'true'

print(window.parent == window) // 'true'

Source

WindowBase get parent;