this面试题记录

# 1.

var name = "window";
var person = {
  name: "person",
  sayName: function () {
    console.log(this.name);
  },
};
function sayName() {
  var sss = person.sayName;
  sss(); // window
  person.sayName(); // person
  (person.sayName)(); // person  相当于 person.sayName()
  (b = person.sayName)(); // window
}
sayName();

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# 2.

var name = "window";
var person1 = {
  name: "person1",
  foo1: function () {
    console.log(this.name);
  },
  foo2: () => console.log(this.name),
  foo3: function () {
    return function () {
      console.log(this.name);
    };
  },
  foo4: function () {
    return () => {
      console.log(this.name);
    };
  },
};
var 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
person1.foo3().call(person2); // person2
person1.foo4()(); // person1
person1.foo4.call(person2)(); // window --> person2 
person1.foo4().call(person2); // person1

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# 3.

var name = "window";
function Person(name) {
  this.name = name;
  this.foo1 = function () {
    console.log(this.name);
  },
  this.foo2 = () => console.log(this.name),
  this.foo3 = function () {
    return function () {
      console.log(this.name);
    };
  },
  this.foo4 = function () {
    return () => {
      console.log(this.name);
    };
  };
}
var person1 = new Person("person1");
var person2 = new Person("person2");
person1.foo1(); // preson1
person1.foo1.call(person2); // person2
person1.foo2(); // person1
person1.foo2.call(person2); // window --> person1
person1.foo3()(); // window
person1.foo3.call(person2)(); // window
person1.foo3().call(person2); // person2
person1.foo4()(); // person1
person1.foo4.call(person2)(); // person2
person1.foo4().call(person2); // person1

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# 4.

var name = "window";
function Person(name) {
  this.name = name;
  this.obj = {
    name: "obj",
    foo1: function () {
      return function () {
        console.log(this.name);
      };
    },
    foo2: function () {
      return () => {
        console.log(this.name);
      };
    },
  };
}
var person1 = new Person("person1");
var person2 = new Person("person2");
person1.obj.foo1()(); // window
person1.obj.foo1.call(person2)(); // window
person1.obj.foo1().call(person2); // person2
person1.obj.foo2()(); // obj
person1.obj.foo2.call(person2)(); // person2
person1.obj.foo2().call(person2); // obj

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上次更新: 2022/10/10, 08:35:47

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