Jquery 尺寸计算器

Question

我有一个朋友在一家销售散热器盖的公司工作，他被要求在他们的网站上添加一个尺寸计算器，这样人们就可以添加他们的测量值和附加值并在线购买。

代码的主要内容正在运行，但由于某种原因，价格在小数点的错误两边被更新。

这是我在 jsfiddle 上的示例代码 https://jsfiddle.net/AndyDyas/tw62Lzop/48/

<div class="wrapper">
    <label for="a">Width:</label>
        <input type="number" name="a" id="a" value="1000" placeholder="1000"  /><br>
    <label for="b">Height:</label>
        <input type="number" name="b" id="b" value="800" placeholder="800" /><br>
    <label for="c">Depth:</label>
        <input type="number" name="c" id="c" value="15" placeholder="15" /><br>   
    <label for="d">Colour:</label>
        <select name="colour" id="d">
          <option value="0">Select</option>
          <option value="-15">Primed (-£15)</option>
          <option value="50">Gloss (+£50)</option>
          <option value="40">Own Colour (£40)</option>
        </select> <br> 
    <label for="e">Grille:</label>
        <select name="grille" id="e">
          <option value="0">Select</option>
          <option value="40">Slats (+£40)</option>
          <option value="75">Regency Brass (+£75)</option>
          <option value="150">Regency Antique / Chrome (+£150)</option>
          <option value="40">Gold / Silver SAA (+£40)</option>
        </select> <br>           
    <label for="total">Result:</label>
        <input type="text" name="total" id="total" value="260.00"  />
    </div>
    <script>
      jQuery(document).ready(function() {
        var price = jQuery('#total').val();
        function compute() {
          var a = parseFloat(jQuery('#a').val() - jQuery('#a').attr("placeholder"));
          var b = parseFloat(jQuery('#b').val() - jQuery('#b').attr("placeholder"));
          var c = parseFloat(jQuery('#c').val() - jQuery('#c').attr("placeholder"));
          var d = parseFloat(jQuery('#d').val()).toFixed(2);
          var e = parseFloat(jQuery('#e').val()).toFixed(2);
          var total = parseFloat(a) + parseFloat(b) + parseFloat(c) + parseFloat(d) + parseFloat(e) + parseFloat(price);
          jQuery('#total').val(parseFloat(total).toFixed(2));
          //alert(a);
        }
        jQuery('#a, #b, #c, #d, #e').change(compute);        
      });;
    </script>
</div>

需要发生的是 width/height/depth 10p 中每多出一毫米就需要将其添加到价格中，但由于某种原因，它会将其添加到小数点的错误一侧（添加 1 英镑而不是10p) 而相反的颜色和格栅以磅为单位。

希望这一堆乱七八糟的东西是有意义的，如果能提供一些帮助，我将不胜感激。

干杯

安迪

Answer 1

我借此机会重写了代码，使其更具可扩展性和灵活性

创建一个对象来保存值和价格变化
在加载时查找这些设置以设置默认值
在更改时验证必填字段
将字段值转换为数字

// this object is the basis for all fields
const prices = {
  "base" : 260,
  "width":  { "min": 1000, "extra": 0.1  },
  "height": { "min":  800, "extra": 0.15 },
  "depth":  { "min": 15,   "extra": 0    } // correct?
};
// helper function to cast to number from string
const toNum = str => isNaN(str) || str.trim() === "" ? 0 : +str;


const compute = e => {
  if (e) e.target.reportValidity(); // show error if field is emptied
  let width = toNum($('#width').val()),
     height = toNum($('#height').val()),
      depth = toNum($('#depth').val()),
     colour = toNum($('#colour').val()),
     grille = toNum($('#grille').val()),
  widthPrice  = (width - prices["width"].min)*prices["width"].extra,
  heightPrice  = (height - prices["height"].min)*prices["height"].extra,
  depthPrice  = (depth - prices["depth"].min)*prices["depth"].extra,
  total = prices["base"] + widthPrice + heightPrice + depthPrice + colour + grille;
  if (total < prices["base"]) total = prices["base"]; // not possible to get less than base price
  $('#total').val(total.toFixed(2));
};


$(function() {
  // setting the defaults based on the object at the top
  ["width","height","depth"]
    .forEach(field => ["min","placeholder","value"]
      .forEach(attr => $('#'+field).attr(attr,prices[field].min))
  )    
      
  compute();
  $('#computeDiv').on("input", compute);
});

label {
  display: inline-block;
  width: 140px;
  text-align: right;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<p>The basic unit is 1000mm wide by 800mm tall and costs £260.00</p>
<p>Every extra 1mm in width is an additional 10 pence per mm and every extra 1mm in height is an extra 15 pence per mm.</p>
<p>The dropdowns are simple extra features at fixed costs there is only the width and height that are dynamic.</p>
<p>So a unit that is 1001mm x 801mm would cost £260.25 (£260 + 10p + 15p) </p>

<div id="computeDiv">
  <label for="width">Width (mm):</label> <input type="number" name="width" id="width" value="" required/><br>
  <label for="height">Height (mm):</label> <input type="number" name="height" id="height" value="" required /><br>
  <label form="depth">Depth (mm):</label> <input type="number" name="depth" id="depth" value="" required /><br>
  <label for="colour">Colour:</label>
  <select name="colour" id="colour">
    <option value="0">Select</option>
    <option value="-15">Primed (-£15)</option>
    <option value="50">Gloss (+£50)</option>
    <option value="40">Own Colour (£40)</option>
  </select><br>
  <label for="grille">Grille:</label>
  <select name="grille" id="grille">
    <option value="0">Select</option>
    <option value="40">Slats (+£40)</option>
    <option value="75">Regency Brass (+£75)</option>
    <option value="150">Regency Antique / Chrome (+£150)</option>
    <option value="40">Gold / Silver SAA (+£40)</option>
  </select><br>
  <label>Total:</label>
  <input type="text" name="total" id="total" value="0.00" readonly />
</div>

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