如何使用'bind'更改函数的上下文？

Question

function greet(){
   return 'Hi ' + this.name;
}
greet = greet.bind({name: 'Tom'});
greet(); // Hi Tom
greet = greet.bind({name: 'Harry'});
greet(); // Hi Tom (Why??)

'bind'应返回一个带有'this'新值的新函数。为什么这不起作用？

Answer 1

将函数绑定到自定义对象后，无法更改。这是原始函数不变的原因：

function greet(){
  return 'Hi ' + this.name;
}
greet1 = greet.bind({name: 'Tom'});
greet1(); // Hi Tom
greet1 = greet.bind({name: 'Harry'});
greet1(); // Hi Harry