var number = 5;
var obj = {
    number: 3,
    fn1: (function () {
        var number;
        this.number *= 2;
        number = number * 2;
        number = 3;
        return function () {
            var num = this.number;
            this.number *= 2;
            console.log(num);
            number *= 3;
            console.log(number);
        }
    })()
}
var fn1 = obj.fn1;
fn1.call(null);
obj.fn1();
console.log(window.number);
// node环境中 -- NaN、9、3、27、5
// 浏览器环境--10、9、3、27、20

1. 首先匿名自执行函数运行后，变为

   var number = 5;
   var obj = {
       number: 3,
       fn1: function() {
           var num = this.number;
           this.number *= 2;
           console.log(num);
           number *= 3;
           console.log(number);
       }
   }
   // 此时
   this.number *= 2; // this为window,所以window.number = 10;
   number = number * 2; // 那么,number为NaN
   number = 3; // number为3；
   // so
   window.number = 10;
   number = 3;
   

资料

一道经典的this面试题 (opens new window)

如何准确判断this指向的是什么？ (opens new window)

Node中this