this

function fn1() {
    console.log(this)  
}
fn1() // window

fn1.call({ x: 100 })  // { x: 100 }

const fn2 = fn1.bind({ x: 200 })
fn2() // { x: 200 }

const zhang = {
  name: ‘zz‘,
  sayHi() {
    // this 即当前对象
    console.log(this)
  },
  wait() {
    setTimeout(function() {
      // this === window
      console.log(this)
    })
  }
}

const zhang1 = {
  name: ‘zz‘,
  sayHi() {
    // this 即当前对象
    console.log(this)
  },
  wait() {
    setTimeout(() => {
      // 箭头函数中的this 永远指向上级作用域的this
      // this 即当前对象
      console.log(this)
    })
  }
}

class People {
  constructor(name) {
    this.name = name
  }
  eat() {
    console.log(`eat: 姓名 ${this.name}`)
  }
}

const xiaoming = new People(‘小明‘) // this === xiaoming 对象