上下文与this指向

var name = 'window'​​
const person1 = {
​  name: 'person1',​
  foo1: function() {​
    console.log(this.name)
​  },
​  foo2: () => {
    console.log(this.name)
​  },​
  foo3: function() {
​    return function() {​
      console.log(this.name)
​    }​
  }
​}​​

const person2 = {
​  name: 'person2'​
}​

person1.foo1() // person1​
person1.foo1.call(person2) // person2

​​person1.foo2() // window​
person1.foo2.call(person2) // window​​

person1.foo3()() // window​
person1.foo3.call(person2)() // window