Window: blur() method

The 
Window.blur() method does nothing.
NOTE:
Historically, this method was the programmatic equivalent of the user shifting focus away
from the current window. This behavior was removed due to hostile sites abusing this functionality.
In Firefox, you can enable the old behavior with the 
dom.disable_window_flip preference.
Syntax
blur()
Parameters
None.
Return value
None (undefined).
Examples
window.blur();
Specifications
Browser compatibility