为什么＆＃39;这个＆＃39;是指第8行的以下函数中的窗口对象？

Question

我很难理解为什么要退出这个＆＃39;在第8行，给我一个Window对象？

var myObject = {
    foo: "bar",
    func: function() {
        var self = this;
        console.log("outer func:  this.foo = " + this.foo);
        console.log("outer func:  self.foo = " + self.foo);
        (function() {
            console.log(this) // here, 'this' is window. Why?
            console.log("inner func:  this.foo = " + this.foo);
            console.log("inner func:  self.foo = " + self.foo);
        }());
    }
};
myObject.func();