Anonymous function's contexgt

var name = "window";
    var f = (function() { alert(this.name); });
    f(); //window
    f.name = "local";
    f();     //still window, the function still run in the context of window
    f.call(f); //local

    var p = { name: "local" };
    p.f = f;
    p.f(); //local
    f.call(p); //local


(function() { alert(this); })(); 
//the defining context is window, it will output window

(function() { alert(this); }).call({}); 
//the defining context is window, but call switch the context