READYSTATE_UNINITIALIZED 0 Default initialization state. The Control has not begun loading any properties.
READYSTATE_LOADING 1 The control is loading its properties.
READYSTATE_LOADED 2 The control has initialized its properties but is not yet interactive.
READYSTATE_INTERACTIVE 3 The control is interactive, but not all of its data is available. (It is downloading a document or frame).
READYSTATE_COMPLETE 4 The control is interactive and all of its data is available. (The current document is fully downloaded).