jQuery过滤器显示数据属性任意或全部

Question

我有一些下拉菜单，用户可以使用这些下拉菜单filter() 下面的 div。这些按钮引用三个单独的数据属性。单击按钮时，会将值添加到数组中，然后我根据这些数组中的值过滤内容。虽然我只有两个下拉菜单，但我运行了四个场景来测试数组是否为空：如果它是空的，我只是测试数据属性的存在，如果有一个值，那么我用它来过滤。

添加第三个过滤器后，我（我认为）有 9 种可能的场景可供测试，并想知道是否有更好的方法来做到这一点。

例如，当我只有两个过滤器时，我的数组可能如下所示：

["united-kingdom", "ireland"] //country
[] //type

var results = $(".collaborator[data-country][data-collaborator_type][data-interest]").filter(function() {
    var $this = $(this);

    if( countryArr.length !== 0 && collaborator_typeArr.length !== 0 ) {
        return countryArr.includes($this.attr("data-country")) && collaborator_typeArr.includes($this.attr("data-collaborator_type"));

    } else if( countryArr.length === 0 && collaborator_typeArr.length === 0 ) {
        return $this.attr('data-country') && $this.attr('data-collaborator_type');

    } else if( countryArr.length === 0 ) {
        console.log('any country');
        return $this.attr('data-country') && collaborator_typeArr.includes($this.attr("data-collaborator_type"));

    } else if( collaborator_typeArr.length === 0 ) {
        console.log('any type');
        return countryArr.includes($this.attr("data-country")) && $this.attr('data-collaborator_type');
    }
});

$('section.collaborator').slideUp('fast');
results.slideDown('fast');

这将在英国和爱尔兰返回任何类型的结果。

我想不出是实现“任何”价值的更好方法。有没有一种方法可以测试“任何”或通配符值，而不是检查数组是否为空。

如果我的数组看起来像这样会怎样

["united-kingdom", "ireland"] //country
["*"] //type

如何过滤以返回所有通配符过滤器？

Answer 1

因为我自己的脚本风格使我能够制作一些可适度扩展的东西，而不必附加案例——无论这些案例可能是简单还是复杂——我改变了脚本中采用的方法。

我还在您的 HTML 中添加了几个组件，尽管您可以根据需要删除这些组件。

也就是说，我采用的方法如下，我尝试在 cmets 中完全解释代码（即使是原始代码中存在的那些部分，也有利于那些将来可能查看问题和答案的人） ):

// delegating the event handler to the '#network-filters'
// element, binding the anonymous function of the on()
// method to act as the 'click' event-handler for the
// click events on those elements contained within that
// match the 'a.filter' selector:
$('#network-filters').on('click', 'a.filter', function(event) {

  // preventing the default action of the <a> elements,
  // preventing the page from following the clicked links:
  event.preventDefault();

  // using the 'let' statement to declare variables, this is
  // possible in ES6-supporting browsers, for older browsers
  // you may have to use 'var' instead (in this situation
  // they're interchangeable).

  // caching the clicked element:
  let clicked = $(this),

    // finding the elements that contain the elements to
    // be filtered (I added the '#results' element):
    results = $('#results .collaborator');

  // toggling the 'toggled' class, to turn it 'on' or 'off'
  // on the clicked <a>, and removing it from the sibling
  // elements:
  clicked.toggleClass('toggled').siblings().removeClass('toggled');

  // caching '.dropdown' elements:
  let dropdowns = $('#network-filters .dropdown'),

  // declaring 'empty' variables for use within
  // the up-coming 'Array.prototype.map()' call:
    filter,
    active,
    filterValue,

  // here we convert the dropdowns jQuery collection into
  // a native JavaScript Array using get(), and then we
  // iterate over that Array using Array.prototype.map():
    selector = dropdowns.get().map(function(dropdown) {
      // 'dropdown' a reference to the current element
      // in the Array of elements over which we're
      // iterating.

      // assigning values to the declared 'empty' variables:
        // here we retrieve the value of the 'data-tax'
        // custom attribute, using the Element.dataset API:
      filter = dropdown.dataset.tax;

        // here we retrieve the element matching the supplied
        // CSS selector contained within the current
        // dropdown element, querySelector returns the first
        // or no matching elements:
      active = dropdown.querySelector('a.filter.toggled');

        // if we have an 'active' element we pass the value
        // of its 'data-filter' attribute to the variable,
        // otherwise we return false:
      filterValue = active ? active.dataset.filter : false;

      // if there was an active element:
      if (active) {
        // we construct a selector to return to the Array
        // we're creating via Array.prototype.map(), that
        // selector takes the form of:
          // 'data-' plus the attribute-value of the
          // 'data-tax' attribute, followed by either an
          // empty string (if the filterValue is exactly
          // equal to 'any') or a string containing '='
          // follwed by the found filterValue; this is
          // all then followed by a ']' character to
          // close the formed attribute-selector:
        return '[data-' + filter + (filterValue === 'any' ? '' : '=' + filterValue) + ']';

      // otherwise:
      } else {
        // we simply return false, if there was no active
        // element:
        return false;
      }

    // we then use Array.prototype.filter(Boolean) to retain
    // only those true/truthy values in the Array
    }).filter(Boolean)

    // and join all array-elements together with an empty string:
    .join('');

  // those results (the '#results .collaborator' elements) are
  // then filtered; those that do not match the created selector
  // are hidden via the slideUp() method:
  results.not(selector).slideUp();

  // then we filter the results array to find those that
  // are hidden (.not(':visible') - using the ':visible'
  // jQuery/Sizzle custom selector) which match the
  // formed selector and apply slideDown() to those
  // elements; this is simply to avoid sliding elements
  // both up and down if they're already visible:
  results.not(':visible').filter(selector).slideDown();

  // here we use a comparison to discover whether or not
  // we have any results; if the number of results elements
  // filtered by the selector is greater than 0, we return
  // true (because we have found some results), otherwise
  // we return false (because there were no matching results):
  let resultsAvailable = results.filter(selector).length > 0;

  // here we find the element (added by me to your HTML) which
  // conveys the 'result-state', and toggle the 'noResult'
  // class using the switch, in which we invert the
  // resultsAvailble variable, so that the class is added if
  // there are no results available, and removed if there are
  // results available (its default state is to be hidden,
  // and shown only if there are no results, this is in the CSS):
  $('#results .resultState').toggleClass('noResult', !resultsAvailable);

});

上面的 JavaScript 加上下面的 HTML：

<div id="network-filters">
  <div class="dropdown" data-tax="country">
    <div class="dropdown-content">
      <a class="filter all" data-filter="any">Show All</a>
      <a class="filter" data-filter="ireland">Ireland</a>
      <a class="filter" data-filter="united-kingdom">United Kingdom</a>

      <!-- the following two <a> elements are added to show how
           easily this approach can be extended; note that there
           is no matching element for the 'Scotland' <a>, to
           demonstrate that the script still works despite that -->
      <a class="filter" data-filter="wales">Wales</a>
      <a class="filter" data-filter="scotland">Scotland</a>
    </div>
  </div>
  <div class="dropdown" data-tax="collaborator">
    <div class="dropdown-content">
      <a class="filter all" data-filter="any">Show All</a>
      <a class="filter" data-filter="artist">Artist</a>
      <a class="filter" data-filter="partner">Partner</a>
    </div>
  </div>
</div>

<!-- the '#results' element was added to logically group the
     elements to be searched together -->
<div id="results">

  <!-- the 'resultState' element was added to visibly inform
       the user that the search was conducted and the lack of
       results is deliberate, rather than the result of a
       broken script -->
  <div class="resultState">No results available for that choice.</div>
  <div class="collaborator" data-country="ireland" data-collaborator="artist">
    <ul>
      <li>country = ireland</li>
      <li>type = artist</li>
    </ul>
  </div>
  <div class="collaborator" data-country="united-kingdom" data-collaborator="partner">
    <ul>
      <li>country = united-kingdom</li>
      <li>type = partner</li>
    </ul>
  </div>

  <!-- the following element was effectively cloned 
       from the same format as the other elements, 
       and dropped in justas a demonstration of how 
       easily this approach can be extended -->
  <div class="collaborator" data-country="wales" data-collaborator="partner">
    <ul>
      <li>country = wales</li>
      <li>type = partner</li>
    </ul>
  </div>
</div>

$('#network-filters').on('click', 'a.filter', function(event) {
  event.preventDefault();

  let clicked = $(this),
    results = $('#results .collaborator');

  clicked.toggleClass('toggled').siblings().removeClass('toggled');

  let dropdowns = $('#network-filters .dropdown'),
    filter,
    active,
    filterValue,
    selector = dropdowns.get().map(function(dropdown) {
      filter = dropdown.dataset.tax;
      active = dropdown.querySelector('a.filter.toggled');
      filterValue = active ? active.dataset.filter : false;

      if (active) {
        return '[data-' + filter + (filterValue === 'any' ? '' : '=' + filterValue) + ']';
      } else {
        return false;
      }
    }).filter(Boolean).join('');

  results.not(selector).slideUp();
  results.not(':visible').filter(selector).slideDown();

  let resultsAvailable = results.filter(selector).length > 0;

  $('#results .resultState').toggleClass('noResult', !resultsAvailable);

});

/* SCSS from JS Fiddle demo (https://jsfiddle.net/davidThomas/5c08shbn/1/)
compiled to CSS via 'http://www.sassmeister.com/' */

.dropdown {
  margin-bottom: 10px;
}
.dropdown a {
  display: inline-block;
  cursor: pointer;
  border: 1px solid grey;
  margin-bottom: 4px;
  padding: 4px 6px;
}
.dropdown a:hover {
  background-color: grey;
}
.dropdown a.toggled {
  /* I just prefer the brighter colour */
  background-color: limegreen;
}
.collaborator {
  background-color: red;
  border: 1px solid red;
  margin-bottom: 10px;
  padding: 4px 6px;
  color: white;
}
.resultState {
  height: 2em;
  line-height: 2em;
  opacity: 0;
  transition: all 0.3s linear;
}
.resultState.noResult {
  opacity: 1;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="network-filters">
  <div class="dropdown" data-tax="country">
    <div class="dropdown-content">
      <a class="filter all" data-filter="any">Show All</a>
      <a class="filter" data-filter="ireland">Ireland</a>
      <a class="filter" data-filter="united-kingdom">United Kingdom</a>
      <a class="filter" data-filter="wales">Wales</a>
      <a class="filter" data-filter="scotland">Scotland</a>
    </div>
  </div>
  <div class="dropdown" data-tax="collaborator">
    <div class="dropdown-content">
      <a class="filter all" data-filter="any">Show All</a>
      <a class="filter" data-filter="artist">Artist</a>
      <a class="filter" data-filter="partner">Partner</a>
    </div>
  </div>
</div>
<div id="results">
  <div class="resultState">No results available for that choice.</div>
  <div class="collaborator" data-country="ireland" data-collaborator="artist">
    <ul>
      <li>country = ireland</li>
      <li>type = artist</li>
    </ul>
  </div>
  <div class="collaborator" data-country="united-kingdom" data-collaborator="partner">
    <ul>
      <li>country = united-kingdom</li>
      <li>type = partner</li>
    </ul>
  </div>
  <div class="collaborator" data-country="wales" data-collaborator="partner">
    <ul>
      <li>country = wales</li>
      <li>type = partner</li>
    </ul>
  </div>
</div>

JS Fiddle demo.

参考资料：

• JavaScript：
  • Array.prototype.filter()。
  • Array.prototype.join()。
  • Array.prototype.map()。
  • Conditional (ternary) operator: assessment ? ifTrue : ifFalse。
  • document.querySelector()。
  • event.preventDefault。
  • HTMLElement.dataset。
• jQuery:
  • filter()。
  • find()。
  • get()。
  • not()。
  • on()。
  • removeClass()。
  • siblings()。
  • slideDown()。
  • slideUp()。
  • toggleClass().
  • :visible。