“‘未定义’不是函数”错误答案

【问题标题】：" 'undefined' is not a function" error“‘未定义’不是函数”错误
【发布时间】：2014-08-03 05:52:28
【问题描述】：

所以，我想编写代码来创建具有随机统计数据的单位。

这是敌人构造函数：

  function Enemy(name, atk, def, hp, mp, xp_val){
    this.name = name;
    this.atk = atk;
    this.def= def;
    this.hp = hp;
    this.max_hp = hp;
    this.mp = mp;
    this.max_mp = mp;
    this.xp_val = xp_val;
    totalEnemies++; 
}

这是创建随机敌人的补充代码。

function createEnemy(name, difficulty){
    var atk = getIntBetween(5, 10);
    var def = getIntBetween (0, 5);
    var hp = getIntBetween(15, 25);
    var mp = getIntBetween(0, 7);
    var xp_val = getIntBetween(5, 10);
    var multiplier;

    if (difficulty === 1 || difficulty.toLowerCase() === "easy"){ multiplier = 1; }
    if (difficulty === 2 || difficulty.toLowerCase() === "average"){ multiplier = 2; }
    if (difficulty === 3 || difficulty.toLowerCase() === "challenge"){ multiplier = 4; }
    if (difficulty === 4 || difficulty.toLowerCase() === "damn"){ multiplier = 7; }
    if (difficulty === 5 || difficulty.toLowerCase() === "nightmare"){ multiplier = 11; }

    atk *= multiplier;
    def *=multiplier;
    hp *= multiplier;
    mp *= multiplier;
    xp_val *= multiplier;

    return new Enemy(name, atk, def, hp, mp, xp_val);
}

我尝试创建一个实例：

var goblin_02 = createEnemy("Goblin Dirtbag", 2);

我得到标题中的错误。这都是为了规避 JS 缺少重载的构造函数，我哪里做错了？

【问题讨论】：

你能告诉我们错误发生在哪一行吗？
也许 getIntBetween 函数没有定义？如果将函数的最后一行更改为此会发生什么？ return [name, atk, def, hp, mp, xp_val];
是的，你认为我应该添加它吗？如果我能告诉你，那就太好了，它可以“运行”得很好，但是一旦它到达这个部分/尝试使用它，我就会遇到问题。

标签： javascript oop object constructor

【解决方案1】：

我对代码进行了一些更改，并且可以正常工作。

<script>
        var totalEnemies = 0;
        function Enemy(name, atk, def, hp, mp, xp_val){
            this.name = name;
            this.atk = atk;
            this.def= def;
            this.hp = hp;
            this.max_hp = hp;
            this.mp = mp;
            this.max_mp = mp;
            this.xp_val = xp_val;
            totalEnemies++; 
        }
        function createEnemy(name, difficulty){
            var atk = getIntBetween(5, 10);
            var def = getIntBetween (0, 5);
            var hp = getIntBetween(15, 25);
            var mp = getIntBetween(0, 7);
            var xp_val = getIntBetween(5, 10);
            var multiplier;

            if (((typeof(difficulty) === "number") &&  (difficulty === 1)) || ((typeof(difficulty) === "string") &&  (difficulty.toLowerCase() === "easy"))){ multiplier = 1; }
            if (difficulty === 2){ multiplier = 2; }
            if (difficulty === 3){ multiplier = 4; }
            if (difficulty === 4){ multiplier = 7; }
            if (difficulty === 5){ multiplier = 11; }

            atk *= multiplier;
            def *=multiplier;
            hp *= multiplier;
            mp *= multiplier;
            xp_val *= multiplier;

            return new Enemy(name, atk, def, hp, mp, xp_val);
        }
        function create() {
            var goblin_02 = createEnemy("Goblin Dirtbag", 2);
            console.log(goblin_02,totalEnemies);
        }
        function getIntBetween(i,j){
            var number = Math.floor((Math.random() * j) + i);
            return number;
        }
    </script>
</head>
<body onload="create()">

</body>

您只需要更改所有 if 块的 if 条件。

【讨论】：

【解决方案2】：

我想它在这里：

if (difficulty === 1 || difficulty.toLowerCase() === "easy"){ multiplier = 1; }

您将 2 传递给 difficulty。它不等于1，所以接下来你实际上是调用2.toLowerCase()。不出所料，这不是真的。

【讨论】：

在您所指的那个下方有一个 if 用于检查。
哦！！所以作用于数字的 toLowerCase() 方法导致了这个问题！谢谢！