Question

我在下面给出了一个公式：

weightdifference = (|crushedWeight - weightBA| / weightBA )* 100%

其中 weightBA 和 crushedWeight 是输入文本的值。我确实做了一个如下所述的功能：

function calDiffWeight() {
    var weightDS = document.getElementById("weightDS");
    var crushedWeight = document.getElementById("crushedWeight");
    var abs = -1;
    var diffWeight = ((crushedWeight - weightDS) * abs) / weightDS * 100;
    document.getElementById("diffWeight").value = diffWeight;
}

并且|crushedWeight - weightBA|中的绝对计算我应该怎么做？

Answer 1

根据您的代码，我做了以下更改：

您获得了weightDS和crushedWeight的元素，但您从未获得这些输入的值;
在将值用于计算之前将值转换为浮点数
使用Math.abs()将数字设为绝对数字。

const
  form = document.getElementById('form');
  
form.addEventListener('submit', onFormSubmit);

function onFormSubmit() {
  event.preventDefault();
  calDiffWeight();
}
function calDiffWeight() {
    var weightDS = parseFloat(document.getElementById("weightDS").value);
    var crushedWeight = parseFloat(document.getElementById("crushedWeight").value);
    var diffWeight = (Math.abs(crushedWeight - weightDS)) / weightDS * 100;
    document.getElementById("diffWeight").value = diffWeight;
}

<form id="form">
  <label>
    WeightDS:
    <input type="number" id="weightDS"/>
  </label>
  <label>
    Crushed Weight:
    <input type="number" id="crushedWeight"/>
  </label>
  
  <button>Calculate</button>
</form>

<p>Result</p>
<input type="number" id="diffWeight"/>

Answer 2

如果weightDS是输入框，我建议使用document.getElementById("weightDS").value;，因为只需getElementById即可获得dom节点。不是它可能包含的任何价值。

这里有一个更大更好的答案How do I get the value of text input field using JavaScript?

Answer 3

方法document.getElementById();返回HTML元素。显然你不能用HTML元素做数学。因此，您可以正确地查找该HTML元素的value属性。因为它是一个字符串，所以将其解析为整数（或根据您的情况浮动）。

var weightDS = parseInt(document.getElementById("weightDS").value);
var crushedWeight = parseInt(document.getElementById(document.getElementById("crushedWeight").value);

Answer 4

在document.getElementById（“weightDS”）

之后使用.value

function calDiffWeight() {
var weightDS = document.getElementById("weightDS").value;
var crushedWeight = document.getElementById("crushedWeight").value;
var abs = -1;
var diffWeight = ((crushedWeight - weightDS) * abs) / weightDS * 100;
document.getElementById("diffWeight").value = diffWeight;
}

Answer 5

document.getElementById('elementId');返回一个DOM元素。为了获得价值，您必须调用value属性。

以下是您的示例的解决方案：

var weightDS = parseInt(document.getElementById("weightDS").value);
var crushedWeight = parseInt(document.getElementById(document.getElementById("crushedWeight").value);

计算一直给出NaN结果

5 个答案: