我似乎无法从一个变量中减去另一个变量

发布于 2024-12-13 12:37:57 字数 1319 浏览 4 评论 0原文

我正在开发一个简单的游戏，并且已经对其进行了编码，以便当您单击攻击按钮时，它应该根据基础和强度生成一个随机数，然后从敌人的生命值中减去该数字，但减去的部分似乎不起作用。它始终输出 NaN。

<head>
    <script>
    var playerHealth=100;
    var enemyHealth=100;
    var strength=10;

    function begin(){
        document.getElementById('playerhealth').innerHTML = playerHealth;
        document.getElementById('enemyhealth').innerHTML = enemyHealth;
        }

    function hitEnemy(){
        var attack=Math.floor(Math.random()*20 + strength);
        var enemyHealth = enemyHealth - attack;
        document.getElementById('damage').innerHTML = attack;   
        document.getElementById('enemyhealth').innerHTML = enemyHealth;
        }

    </script>
</head>
<body onload="begin()">
        <input type="button" name="doit" id="doit" value="Attack!" onclick="hitEnemy();">
        <br /><span>playerhealth</span>
        <div style="font-size:3em;" id="playerhealth"></div>
        <span>enemyhealth</span>
        <div style="font-size:3em;" id="enemyhealth"></div>
        <br />
        <span>You Did:</span><span style="font-size:3em;" id="damage"></span><span>damage</span>

</body>

这可能与没有明确确保它们是整数有关，但我不知道该怎么做。

原文

I'm working on a simple game and I've gotten as far as coding it so that when you click on an attack button it should generate a random number based on a base and strength then subtract that from the enemy's health but the subtracting part doesn't seem to work. It always outputs NaN.

<head>
    <script>
    var playerHealth=100;
    var enemyHealth=100;
    var strength=10;

    function begin(){
        document.getElementById('playerhealth').innerHTML = playerHealth;
        document.getElementById('enemyhealth').innerHTML = enemyHealth;
        }

    function hitEnemy(){
        var attack=Math.floor(Math.random()*20 + strength);
        var enemyHealth = enemyHealth - attack;
        document.getElementById('damage').innerHTML = attack;   
        document.getElementById('enemyhealth').innerHTML = enemyHealth;
        }

    </script>
</head>
<body onload="begin()">
        <input type="button" name="doit" id="doit" value="Attack!" onclick="hitEnemy();">
        <br /><span>playerhealth</span>
        <div style="font-size:3em;" id="playerhealth"></div>
        <span>enemyhealth</span>
        <div style="font-size:3em;" id="enemyhealth"></div>
        <br />
        <span>You Did:</span><span style="font-size:3em;" id="damage"></span><span>damage</span>

</body>

It may have something to do with not specifically making sure that they're integers but I'm not sure how to do that.

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猛虎独行 2024-12-20 12:37:57

因为您在 hitEnemy 函数中重新定义了敌人健康变量。删除 var 来修复它。

 function hitEnemy(){
        var attack=Math.floor(Math.random()*20 + strength);
        enemyHealth = enemyHealth - attack;
        document.getElementById('damage').innerHTML = attack;   
        document.getElementById('enemyhealth').innerHTML = enemyHealth;
        }

because you redefine the enemyHealth var inside hitEnemy function. Remove the var to fix it.

 function hitEnemy(){
        var attack=Math.floor(Math.random()*20 + strength);
        enemyHealth = enemyHealth - attack;
        document.getElementById('damage').innerHTML = attack;   
        document.getElementById('enemyhealth').innerHTML = enemyHealth;
        }

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吝吻 2024-12-20 12:37:57

这是最直接的问题。您需要从 hitEnemy 内的 enemyHealth 声明中删除 var。这将创建一个名为 enemyHealth 的新变量，而不是修改第一个变量。

enemyHealth = enemyHealth - parseFloat(attack);

此外，您应该在每次 hitEnemy 调用结束时调用 begin 以便更新分数。这是代码的工作版本

http://jsfiddle.net/YbCay/

Here is the most immediate problem. You need to remove var from the enemyHealth decalaration inside of hitEnemy. This creates a new variable named enemyHealth intsead of modifying the first one.

enemyHealth = enemyHealth - parseFloat(attack);

Additionally you should be calling begin at the end of every hitEnemy call in order to update the scores. Here's a working version of the code

http://jsfiddle.net/YbCay/

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万劫不复 2024-12-20 12:37:57

添加到 Jared 的响应中...

var enemyHealth = enemyHealth - attack;

是...的简写...

var enemyHealth;
enemyHealth = enemyHealth - attack;

首先，enemyHealth 在 hitEnemy 范围内被定义为 undefined*。现在，存在名为 enemyHealth 的两个变量，但内部变量“隐藏”了外部变量，导致无法引用外部变量。因此，从 undefined 中减去 attack，产生 NaN。

*这听起来很荒谬，我知道

To add to Jared's response...

var enemyHealth = enemyHealth - attack;

is shorthand for...

var enemyHealth;
enemyHealth = enemyHealth - attack;

First, enemyHealth is defined as undefined* within the scope of hitEnemy. Now, two variables named enemyHealth exist, but the inner one "shadows" the outer one, making it impossible to refer to the outer one. So, attack is subtracted from undefined, producing NaN.

* which sounds nonsensical, I know

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~没有更多了~