javascript - 当修改一个类的一个实例的属性时，该类的所有实例的属性都会改变

Question

我的背景主要是 Python 和 C#，但我正在帮助一位正在参加 JavaScript 入门类(class)的 friend 学习编码。该类(class)本周结束，但它从未涉及如何用 JavaScript 编写类(class)，所以我想我应该很快地拼凑一个例子来说明它们是如何工作的。唯一的问题是，每当我更改类的一个实例的属性值时，该属性在所有实例上都会更改。有什么办法可以做到这一点吗？

基本上当我对 troll1 造成伤害时，troll2 的生命值应该仍然是 10(反之亦然)。相反，如果我对 troll1 造成三点伤害，那么 troll2 和 troll3 的生命值也会变为 7。

我曾尝试在构造函数之外设置健康，但随后在调用类方法时出现错误，提示未定义健康(无论我使用 this.health 还是仅使用健康)。

这是我做的例子的html和js:

class trollEnemy {

  constructor() {
    this.health = 10;
  }


  takeDamage(damageAmount) {
    this.health = this.health - damageAmount;
    if (this.health > 0) {
      document.getElementById("outputDiv").innerHTML = "Dealt " + damageAmount + " damage to the troll, the troll now has " + this.health + " health left";
    } else {
      document.getElementById("outputDiv").innerHTML = "Dealt " + damageAmount + " damage to the troll, the troll is now dead";
    }
  }

  getHealth() {
    if (this.health > 0)
      document.getElementById("outputDiv").innerHTML = "The troll has " + this.health + " health left";
    else
      document.getElementById("outputDiv").innerHTML = "The troll is dead";
  }

}

var troll1 = new trollEnemy();
var troll2 = new trollEnemy();
var troll3 = new trollEnemy();

function generateNewTroll(trollNumber) {
  switch (trollNumber) {
    case 1:
      troll1 = new trollEnemy();
    case 2:
      troll2 = new trollEnemy();
    case 3:
      troll3 = new trollEnemy();
  }
}

function damageTroll(trollNumber) {
  switch (trollNumber) {
    case 1:
      troll1.takeDamage(document.getElementById("trollDamageAmount").value);
    case 2:
      troll2.takeDamage(document.getElementById("trollDamageAmount").value);
    case 3:
      troll3.takeDamage(document.getElementById("trollDamageAmount").value);
  }
}

function checkTrollHealth(trollNumber) {
  switch (trollNumber) {
    case 1:
      troll1.getHealth();
    case 2:
      troll2.getHealth();
    case 3:
      troll3.getHealth();
  }
}

<button onclick="generateNewTroll(1)">Generate New Troll #1</button><button onclick="damageTroll(1)">Deal Damage To Troll #1</button> <button onclick="checkTrollHealth(1)">Check Troll #1 Health</button><br>
<button onclick="generateNewTroll(2)">Generate New Troll #2</button><button onclick="damageTroll(2)">Deal Damage To Troll #2</button> <button onclick="checkTrollHealth(2)">Check Troll #2 Health</button><br>
<button onclick="generateNewTroll(3)">Generate New Troll #3</button><button onclick="damageTroll(3)">Deal Damage To Troll #3</button> <button onclick="checkTrollHealth(3)">Check Troll #3 Health</button> Enter the amount of damage you want to deal to a
troll: <input type="text" id="trollDamageAmount">

<br>

<div id="outputDiv">Test</div>

Answer 1

您需要在switch 中加入break 语句声明，否则他们都会被调用:

switch(trollNumber)
    {
        case 1:
            troll1.getHealth();
            break
        case 2:
            troll2.getHealth();
            break
        case 3:
            troll3.getHealth();
            break
    }

没有中断的事情通过例如:

let trollNumber = 1
switch(trollNumber)
    {
        case 1:
            console.log(1)
        case 2:
           console.log(2)
        case 3:
           console.log(3)
    }

如果将巨魔存储在数组中，您可能会更快乐。这将简化一切。例如，您可以编写如下函数:

function damageTroll(trollNumber){
   trolls[trollNumber].getHealth()
}