在过滤选择框时选择一个值

Question

我在下面的脚本中有问题，如果"产品颜色"更改(选择(以上，则在果实下拉中的第一个预选/过滤项目实际上是上一个数组列表中的最后一个，它应该是该列表上的第一个。

• 因此，如果我选择绿色，它将过滤到："全"，"水果1"，"水果3"，"水果5"
• 但是，当我切换到黄色时，水果下拉列表中的预选价值将是上一个列表中的最后一个，所以"水果5"

我如何强制它始终成为第一个值？

示例如下：

$(function() {
  var $product = $('[name="filter-product"]');
  var $fruits = $('[name="filter-fruits"]');
  var $fruitsList = $fruits.find('option').clone();
  var fruit = {
    "Green": ["All", "Fruit 1", "Fruit 3", "Fruit 5"],
    "Yellow": ["All", "Fruit 1", "Fruit 3", "Fruit 4", "Fruit 5"]
  }
  $product.change(function() {
    var $selectedProduct = $(this).find('option:selected').text();
    $fruits.html($fruitsList.filter(function() {
      return $.inArray($(this).text(), fruit[$selectedProduct]) >= 0;
    }));
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h4>Color</h4>
<select name="filter-product">
  <option value="All">All</option>
  <option value="yellow">Yellow</option>
  <option value="green">Green</option>
</select>
<h4>Fruit</h4>
<select name="filter-fruits">
  <option value="All">All</option>
  <option value="fruit1">Fruit 1</option>
  <option value="fruit2">Fruit 2</option>
  <option value="fruit3">Fruit 3</option>
  <option value="fruit4">Fruit 4</option>
  <option value="fruit5">Fruit 5</option>
</select>

Answer 1

要执行此操作，您可以在更新option元素之后手动将SELECT返回的selectedIndex设置为0：

$(function() {
  var $product = $('[name="filter-product"]');
  var $fruits = $('[name="filter-fruits"]');
  var $fruitsList = $fruits.find('option').clone();
  var fruit = {
    "Green": ["All", "Fruit 1", "Fruit 3", "Fruit 5"],
    "Yellow": ["All", "Fruit 1", "Fruit 3", "Fruit 4", "Fruit 5"]
  }
  $product.change(function() {
    var $selectedProduct = $(this).find('option:selected').text();
    $fruits.html($fruitsList.filter(function() {
      return $.inArray($(this).text(), fruit[$selectedProduct]) >= 0;
    }));
    $fruits[0].selectedIndex = 0; // select the first option
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h4>Color</h4>
<select name="filter-product">
  <option value="All">All</option>
  <option value="yellow">Yellow</option>
  <option value="green">Green</option>
</select>
<h4>Fruit</h4>
<select name="filter-fruits">
  <option value="All">All</option>
  <option value="fruit1">Fruit 1</option>
  <option value="fruit2">Fruit 2</option>
  <option value="fruit3">Fruit 3</option>
  <option value="fruit4">Fruit 4</option>
  <option value="fruit5">Fruit 5</option>
</select>

Answer 2

$(function() {
  var $product = $('[name="filter-product"]');
  var $fruits = $('[name="filter-fruits"]');
  var $fruitsList = $fruits.find('option').clone();
  var fruit = {
    "Green": ["All", "Fruit 1", "Fruit 3", "Fruit 5"],
    "Yellow": ["All", "Fruit 1", "Fruit 3", "Fruit 4", "Fruit 5"]
  }
  $product.change(function() {
    var $selectedProduct = $(this).find('option:selected').text();
    $fruits.html($fruitsList.filter(function() {
      return $.inArray($(this).text(), fruit[$selectedProduct]) >= 0;
    }));
    $fruits[0].selectedIndex = 0;
    
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h4>Color</h4>
<select name="filter-product">
  <option value="All">All</option>
  <option value="yellow">Yellow</option>
  <option value="green">Green</option>
</select>
<h4>Fruit</h4>
<select name="filter-fruits">
  <option value="All">All</option>
  <option value="fruit1">Fruit 1</option>
  <option value="fruit2">Fruit 2</option>
  <option value="fruit3">Fruit 3</option>
  <option value="fruit4">Fruit 4</option>
  <option value="fruit5">Fruit 5</option>
</select>

Answer 3

$(function() {
  var $product = $('[name="filter-product"]');
  var $fruits = $('[name="filter-fruits"]');
  
  var fruit = {
    "Green": ["All", "Fruit 1", "Fruit 3", "Fruit 5"],
    "Yellow": ["All", "Fruit 1", "Fruit 3", "Fruit 4", "Fruit 5"]
  }
  $product.change(function() {
//moving this clone function inside onclick can help;
  var $fruitsList = $fruits.find('option').clone();
    var $selectedProduct = $(this).find('option:selected').text();
    $fruits.html($fruitsList.filter(function() {
      return $.inArray($(this).text(), fruit[$selectedProduct]) >= 0;
    }));
  });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<h4>Color</h4>
<select name="filter-product">
  <option value="All">All</option>
  <option value="yellow">Yellow</option>
  <option value="green">Green</option>
</select>
<h4>Fruit</h4>
<select name="filter-fruits">
  <option value="All">All</option>
  <option value="fruit1">Fruit 1</option>
  <option value="fruit2">Fruit 2</option>
  <option value="fruit3">Fruit 3</option>
  <option value="fruit4">Fruit 4</option>
  <option value="fruit5">Fruit 5</option>
</select>