无法更改 Javascript 中数字输入的默认值

Question

我正在使用 Javascript（还不熟悉 Angular 之类的框架），并试图从我的 HTML 中获取并显示数字输入的值，但是当我运行执行此操作的函数时，默认值为“1 " 来自 HTML 似乎是唯一使用的，即使我通过单击箭头将网站本身的输入更改为 10。

我认为就语法而言我已经正确编写了代码，所以我唯一的想法是也许输入必须以某种形式包装，并且“滚动”按钮更改为 type="submit “？

这是一个指向codepen 的链接，其中包含损坏的代码，以及下面涉及的部分的sn-ps。

var displayScreen = document.getElementById("display-message");
var rollButton = document.getElementById("roll-button");

//Variable to tell the rollDice() function how many times to roll dice.
var numDice = document.getElementById("num-dice").value;

//Dice Array to hold the results of the rollDice() function, gets cleared after each use.
var diceTotal = [];

//Event listener for the "roll" button
rollButton.addEventListener("click", rollDice);

//Make this function display a roll result
function displayMessage() {

  displayScreen.innerText = diceTotal[0];
}

//Generate a random number between 1 and diceType, and set the rolledNumber variable to its result
function rollDice() {

  //Nothing currently changes numDice, so it keeps default value="1".

  result = 0;
  var roll = Math.floor(Math.random() * diceType) + 1;

  for (var i = 0; i < numDice; i++) {
    result += roll;
  }

  diceTotal[0] = result;

  displayMessage();
}

<div id="dice-display-div">

  <!--
                We want to display the dice roll total, any applied bonuses, and then the final total
                together in this div, possibly as separate <h2> elements.
            -->

  <h2 id="display-message">Click "Roll" to Begin</h2>

</div>

<div id="roll-button-div">

  <label class="roll-button-label" for="num-dice" id="num-dice-label">Number of Dice: </label>
  <input class="roll-button-item" type="number" id="num-dice" name="num-dice" value="1" min="1" max="10">

  <label class="roll-button-label" for="bonus" id="bonus-label">Bonus (or Negative): </label>
  <input class="roll-button-item" type="number" id="bonus" name="bonus" value="0" min="-10" max="10">

  <button class="roll-button-item" id="roll-button">Roll</button>

</div>

Answer 1

首先，您应该在 for 循环中调用 Math.random()，否则您只会随机生成一个数字，并且所有骰子都将具有相同的数字。其次，您应该在函数内部分配numDice，以便它重新检查并分配当前值，而不是在页面渲染开始时分配：

var displayScreen = document.getElementById("display-message");
var rollButton = document.getElementById("roll-button");



//Dice Array to hold the results of the rollDice() function, gets cleared after each use.
var diceTotal = [];

//Event listener for the "roll" button
rollButton.addEventListener("click", rollDice);

//Make this function display a roll result
function displayMessage() {

    displayScreen.innerText = diceTotal[0];
}

//Generate a random number between 1 and diceType, and set the rolledNumber variable to its result
function rollDice() {
   //Variable to tell the rollDice() function how many times to roll dice.
   var numDice = document.getElementById("num-dice").value; //assign this upon function call so it checks it each time the button is clicked to get the latest value
   //Nothing currently changes numDice, so it keeps default value="1".

   result = 0;
   var roll = 0

   for (var i = 0; i < numDice; i++) {
       roll =  Math.floor(Math.random() * diceType) + 1; //call random on each dice roll
       result += roll;
   }

   diceTotal[0] = result;

  displayMessage();
}