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Comments (2)

dev-zuo avatar dev-zuo commented on August 25, 2024

这里确实有问题,函数不是构造函数,没有 new,调用时 this 都是指向 window。不会打印函数内对应的变量 a

应该改为

var a = 5
function callback() {
  console.log('-- callback this', this, this.a, '--')
}
function validate() {
  console.log('-- validate this', this, this.a, '--')
}
function showPrompt(title, validate, callback) {
  validate()
  callback()
}
showPrompt('1', validate, callback) // 5 5 
showPrompt('1', validate.bind({a: 2}), callback.bind({a: 1})) // 2 1

或者

var a = 5
var callback = {
  a: 1,
  handler() {
    console.log(this, this.a)
  }
}
var validate = {
  a: 2,
  handler() {
    console.log(this, this.a)
  }
}
function showPrompt(title, validate, callback) {
  validate()
  callback()
}
showPrompt('1', validate.handler, callback.handler) // 5 5 
showPrompt('1', validate.handler.bind(validate), callback.handler.bind(callback)) // 2 1

from fedemo.

alphagege avatar alphagege commented on August 25, 2024

谢谢,看了您的学习笔记,对我扩展知识广度帮助很大,感谢!

from fedemo.

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