Javascript - 如何为函数设置'this'变量

function greet() {
  console.log('Hello, ' + this.name);
}

var person = {
  name: 'John'
};

greet.call(person); // 输出 "Hello, John"
greet.apply(person); // 输出 "Hello, John"

function greet() {
  console.log('Hello, ' + this.name);
}

var person = {
  name: 'John'
};

var boundGreet = greet.bind(person);
boundGreet(); // 输出 "Hello, John"

var person = {
  name: 'John',
  greet: function() {
    setTimeout(() => {
      console.log('Hello, ' + this.name);
    }, 1000);
  }
};

person.greet(); // 输出 "Hello, John"