SOURCE

class test {//这里我老是习惯写class test = {}
  constructor(){
    console.info('in constructor')
    this.key = "value"
  }
  func(){
    console.info('func   '+this.key)
  }
}
console.info("000")
var te = new test();
te.func()

class bar extends test{//extends类继承
  constructor(p){
    super(p)//调用父类的constructor
  }
  subFunc(){
    
  }
}
var b = new bar();
console.info(b)