This page tests what happens when a getter / setter on the window object conflicts with another property or declared variable.

window.x is: 1
typeof window.__lookupGetter__("x") is: undefined
window.x is: 2
typeof window.__lookupSetter__("x") is: undefined
window.y is: window.y __getter__
typeof window.__lookupGetter__("y") is: function
window.y __setter__ called
window.y is: window.y __getter__
typeof window.__lookupSetter__("y") is: function
window.z __setter__ called
typeof window.__lookupSetter__("z") is: undefined