javascript - 如何使用具有多个子原型(prototype)对象的原型(prototype)嵌套对象和共享变量？

Question

我是 JavaScript 的新手，我想了解继承的工作原理，我以前使用过 C++，并且很容易处理从主类到它们的后代的变量，我尝试过原型(prototype)方法，但工作起来并不那么容易。这是我的代码...正确的方法是什么？？？

function main() {
  this.name = "main object, name";

}
main.prototype.LevelA1 = function() {
  return "LevelA1 method " + this.name; //this level read this.name right
}
main.prototype.LevelA = function() {
  this.a = "laaaa"
  return "LevelA " + this.name; //variable this.name is visible

}

main.prototype.LevelA.LevelB = function() {

  return this.name + " Level B " + this.a //this.name undefined
}
main.prototype.LevelA.LevelB.LevelC = function() {
  return "level C" + this.name; //this.name not visible and not produce error
}
main.prototype.LevelA.LevelB.LevelC.LevelD = function() {
  this.bb = "variable of levelD"
  return "Level D " + this.bb + this.name; //this.name not visible and ot produce error

}
m = new main();
console.log(m.LevelA());
console.log(m.LevelA.LevelB());
console.log(m.LevelA.LevelB.LevelC());
console.log(m.LevelA.LevelB.LevelC.LevelD());
var cc = new m.LevelA.LevelB.LevelC.LevelD();
console.log(cc.bb);

Answer 1

您正在设置新函数而不是设置新原型(prototype)，因此每个新函数的词法上下文与 Main.prototype 无关。

我建议您使用类来处理您的逻辑。

这种方法将“Level”函数包装在一个从 Main 类扩展的类中。

class Main {
  constructor() {
    this.name = "main object, name";
  }
}

class MainLevel extends Main {
  LevelA1() {
    return "LevelA1 method " + this.name; //this level read this.name right  
  }

  LevelA() {
    this.a = "laaaa"
    return "LevelA " + this.name; //variable this.name is visible
  }

  LevelB() {
    return this.name + " Level B " + this.a //this.name undefined
  }

  LevelC() {
    return "level C" + this.name; //this.name not visible and not produce error
  }

  LevelD() {
    this.bb = "variable of levelD"
    return "Level D " + this.bb + this.name; //this.name not visible and ot produce error

  }
}

let m = new MainLevel();
console.log(m.LevelA());
console.log(m.LevelB());
console.log(m.LevelC());
console.log(m.LevelD());