Javascript 子类别SELECT.append（“+msProducts[i]+”）； } }else if（业务==“苹果”）{ //如果Apple然后遍历appleProducts数组，并将值作为选项元素附加到子类别select元素 对于（var i=0；i

这里有一个有用的工具：

这里是实现所需功能的另一种jQuery方法（注释并解释）

添加了引导类来为外观选择元素

HTML

<select id="mainCategorySelect" name="mainCategorySelect" class="form-control">
    <option>Select category</option>
</select>

<select id="subCategorySelect" name="subCategorySelect" class="form-control"></select>

<select name="brand" id="brand">
  <option value="-1">--------------------</option>
  <option value="apple">Apple</option>
  <option value="microsoft">Microsoft</option>
</select>
<select id="model">
  <option value="-1">--------------------</option>
</select>

选择类别

JS

// Wait for the dom to be ready
$(function () {

    // For the sake of this example our business and products are arrays
    var businesses = ["Microsoft","Apple"],
        msProducts = ["Microsoft Phone","Microsoft Office","Microsoft Windows 10"],
        appleProducts = ["Apple iPhone","Apple iPad","Apple iPod","Apple iSomething"],

        // Declare variables for the select elements
        mainCategorySelect = $('#mainCategorySelect'),
        subCategorySelect = $('#subCategorySelect');

    // Iterate thorugh businesses and populate the main select element
    for (var i = 0; i < businesses.length; i++) {
        mainCategorySelect.append("<option value='"+businesses[i]+"'>"+businesses[i]+"</option>");
    }

    // using jQuery .on('change')
    mainCategorySelect.on('change', function() {
        // Always clear the sub category select when main select element value is changed
        subCategorySelect.empty();
        // Retrieve the value of the main select element
        var business = $(this).val();
        // if else statement to deside which products to list in the sub category select element
        if (business == "Microsoft") {
            // if Microsoft then iterate through the msProducts array and append the values as option elements to the sub category select element
            for (var i = 0; i < msProducts.length; i++) {
                subCategorySelect.append("<option value='"+msProducts[i]+"'>"+msProducts[i]+"</option>");
            }
        } else if(business == "Apple") {
            // if Apple then iterate through the appleProducts array and append the values as option elements to the sub category select element
            for (var i = 0; i < appleProducts.length; i++) {
                subCategorySelect.append("<option value='"+appleProducts[i]+"'>"+appleProducts[i]+"</option>");
            }
        }
        // When the user changes the value of the sub category select element the do something with it
        subCategorySelect.on('change', function() {
            alert($(this).val());
        });
    });
});

//等待dom准备就绪
$（函数（）{
//在本例中，我们的业务和产品是阵列
var Business=[“微软”、“苹果”]，
msProducts=[“Microsoft手机”、“Microsoft Office”、“Microsoft Windows 10”]，
appleProducts=[“苹果iPhone”、“苹果iPad”、“苹果iPod”、“苹果东西”]，
//为select元素声明变量
mainCategorySelect=$（“#mainCategorySelect”），
子类别选择=$（“#子类别选择”）；
//迭代thorugh业务并填充主选择元素
对于（var i=0；i

---

这里有一个可行的办法：

如果产品线扩展超过一定数量，那么使用明确的条件进行验证将使这一点在将来难以维持。如其他人所示，使用某种形式的数组是一种更好的方法

另外，尽管jQuery是一个很棒的库，但不要忘记香草JavaScript。如果代码编写得好，即使它看起来更复杂，普通JavaScript也应该比jQuery的运行速度更快。考虑到这一点，这里有另一个解决方案，这次是“或多或少”的纯JavaScript——我在准备就绪的时候离开了

HTML

<select id="mainCategorySelect" name="mainCategorySelect" class="form-control">
    <option>Select category</option>
</select>

<select id="subCategorySelect" name="subCategorySelect" class="form-control"></select>

<select name="brand" id="brand">
  <option value="-1">--------------------</option>
  <option value="apple">Apple</option>
  <option value="microsoft">Microsoft</option>
</select>
<select id="model">
  <option value="-1">--------------------</option>
</select>

--------------------
苹果
微软
--------------------

JavaScript

var products = {
  apple: [
    { name: "iPhone 6 Plus", model: "iphone_6plus" },
    { name: "iPhone 6", model: "iphone_6" },
    { name: "iPhone 5s", model: "iphone_5s" },
    { name: "iPhone 5c", model: "iphone_5c" }
  ],
  microsoft: [
    { name: "Windows 10", model: "windows_10" },
    { name: "Windows 8", model: "windows_8" },
    { name: "Office 2015", model: "office_2015" },
    { name: "Office 2014", model: "office_2014" }
  ]
};

function create_option(text, value) {
  var option = document.createElement("option");
  var txt = document.createTextNode(text);

  option.value = value;
  option.appendChild(txt);

  return option;
}

function populate_model(selection) {
  var select = document.getElementById("model");
  var i, l;

  if ((selection == -1) || (products[selection] === undefined))
    return false;

  while (select.lastChild)
    select.removeChild(select.lastChild);

  select.appendChild(document.createElement("option").appendChild(document.createTextNode("--------------------")));

  for (i = 0, l = products[selection].length; i < l; i++)
    select.appendChild(create_option(products[selection][i].name, products[selection][i].model));
}

$(document).ready(function() {
  var brand = document.getElementById("brand");

  brand.onchange = function() {
    populate_model(this.options[this.selectedIndex].value);
  };

  brand.value = -1;
});

var产品={
苹果公司：[
{名称：“iphone6plus”，型号：“iphone6plus”}，
{名称：“iPhone 6”，型号：“iPhone_6”}，
{名称：“iPhone 5s”，型号：“iPhone_5s”}，
{名称：“iPhone 5c”，型号：“iPhone_5c”}
],
微软：[
{名称：“Windows 10”，型号：“Windows_10”}，
{名称：“Windows 8”，型号：“Windows_8”}，
{名称：“Office 2015”，型号：“Office_2015”}，
{名称：“Office 2014”，型号：“Office_2014”}
]
};
函数创建_选项（文本、值）{
var option=document.createElement（“选项”）；
var txt=document.createTextNode（文本）；
option.value=值；
option.appendChild（txt）；
返回选项；
}
函数类型（选择）{
var select=document.getElementById（“模型”）；
变量i，l；
if（（选择==-1）| |（产品[选择]==未定义））
返回false；
while（选择.lastChild）
select.removeChild（select.lastChild）；
选择.appendChild（document.createElement（“选项”）.appendChild（document.createTextNode（“--------------------------”））；
对于（i=0，l=products[selection]。长度；i

---

我还更新了您的JSFIDLE:

使用显式条件进行验证，如果产品线扩展超过一定数量，这将使将来很难维护。如其他人所示，使用某种形式的数组是一种更好的方法

另外，尽管jQuery是一个很棒的库，但不要忘记香草JavaScript。如果代码编写得好，即使它看起来更复杂，普通JavaScript也应该比jQuery的运行速度更快。考虑到这一点，这里有另一个解决方案，这次是“或多或少”的纯JavaScript——我在准备就绪的时候离开了

HTML

<select id="mainCategorySelect" name="mainCategorySelect" class="form-control">
    <option>Select category</option>
</select>

<select id="subCategorySelect" name="subCategorySelect" class="form-control"></select>

<select name="brand" id="brand">
  <option value="-1">--------------------</option>
  <option value="apple">Apple</option>
  <option value="microsoft">Microsoft</option>
</select>
<select id="model">
  <option value="-1">--------------------</option>
</select>

--------------------
苹果
微软
--------------------

JavaScript

var products = {
  apple: [
    { name: "iPhone 6 Plus", model: "iphone_6plus" },
    { name: "iPhone 6", model: "iphone_6" },
    { name: "iPhone 5s", model: "iphone_5s" },
    { name: "iPhone 5c", model: "iphone_5c" }
  ],
  microsoft: [
    { name: "Windows 10", model: "windows_10" },
    { name: "Windows 8", model: "windows_8" },
    { name: "Office 2015", model: "office_2015" },
    { name: "Office 2014", model: "office_2014" }
  ]
};

function create_option(text, value) {
  var option = document.createElement("option");
  var txt = document.createTextNode(text);

  option.value = value;
  option.appendChild(txt);

  return option;
}

function populate_model(selection) {
  var select = document.getElementById("model");
  var i, l;

  if ((selection == -1) || (products[selection] === undefined))
    return false;

  while (select.lastChild)
    select.removeChild(select.lastChild);

  select.appendChild(document.createElement("option").appendChild(document.createTextNode("--------------------")));

  for (i = 0, l = products[selection].length; i < l; i++)
    select.appendChild(create_option(products[selection][i].name, products[selection][i].model));
}

$(document).ready(function() {
  var brand = document.getElementById("brand");

  brand.onchange = function() {
    populate_model(this.options[this.selectedIndex].value);
  };

  brand.value = -1;
});

var产品={
苹果公司：[
{名称：“iphone6plus”，型号：“iphone6plus”}，
{名称：“iPhone 6”，型号：“iPhone_6”}，
{名称：“iPhone 5s”，型号：“iPhone_5s”}，
{名称：“iPhone 5c”，型号：“iPhone_5c”}
],
微软：[
{nam