jQuery自定義選擇器代碼

Question

我正在學習jQuery，在閱讀書籍時，有一個代碼，您正在製作自定義選擇器。下面是代碼

(function($) { 
    $.extend($.expr[':'], { 
     group: function(element, index, matches, set) { 
      var num = parseInt(matches[3], 10); 
      if (isNaN(num)) { 
       return false; 
      } 
      return index % (num * 2) < num; 
     } 
    }); 
})(jQuery); 

，並在這裏呼籲

$(document).ready(function() { 
    function stripe() { 
     $('#news').find('tr.alt').removeClass('alt'); 
     $('#news tbody').each(function() { 
      $(this).children(':visible').has('td') 
       .filter(':group(3)').addClass('alt'); 
     }); 
    } 

    stripe(); 

}); 

我知道.filter（）運行對每個子元素。假設如果我的tbody元素有4個tr（行），那麼對每個tr運行.filter（隱式迭代）。 現在，當調用.filter（'：group（3）'）時，我注意到傳遞給：group函數的參數是。

首次成爲

組：功能（元件，索引，火柴，設置）

元件是TR，索引是0，符合項目成爲[「：組（3）「，」組「，」「，」3「]和組變成[tr，tr，tr，tr，tr]

現在，我設置了一組，每個tbody標籤都有tr的數量，這成爲了set數組。但是請告訴我，parseInt（匹配[3]，10）如何工作？

我想問問jQuery如何製作匹配數組。我只寫：組（3）。如何將匹配值設置爲參數列表中的這些值？

這裏是HTML的代碼片段

<table id="news"> 
    <thead> 
     <tr> 
      <th>Date</th> 
      <th>Headline</th> 
      <th>Author</th> 
      <th>Topic</th> 
     </tr> 
    </thead> 

    <tbody> 
     <tr> 
      <th colspan="4">2011</th> 
     </tr> 
     <tr> 
      <td>Apr 15</td> 
      <td>jQuery 1.6 Beta 1 Released</td> 
      <td>John Resig</td> 
      <td>Releases</td> 
     </tr> 
     <tr> 
      <td>Feb 24</td> 
      <td>jQuery Conference 2011: San Francisco Bay Area</td> 
      <td>Ralph Whitbeck</td> 
      <td>Conferences</td> 
     </tr> 
     <tr> 
      <td>Feb 7</td> 
      <td>New Releases, Videos &amp; a Sneak Peek at the jQuery UI Grid</td> 
      <td>Addy Osmani</td> 
      <td>Plugins</td> 
     </tr> 
     <tr> 
      <td>Jan 31</td> 
      <td id="release">jQuery 1.5 Released</td> 
      <td>John Resig</td> 
      <td>Releases</td> 
     </tr> 
     <tr> 
      <td>Jan 30</td> 
      <td>API Documentation Changes</td> 
      <td>Karl Swedberg</td> 
      <td>Documentation</td> 
     </tr> 
    </tbody> 

    <tbody> 
     <tr> 
      <th colspan="4">2010</th> 
     </tr> 
     <tr> 
      <td>Nov 23</td> 
      <td>Team Spotlight: The jQuery Bug Triage Team</td> 
      <td>Paul Irish</td> 
      <td>Community</td> 
     </tr> 
     <tr> 
      <td>Oct 4</td> 
      <td>New Official jQuery Plugins Provide Templating, Data Linking and Globalization</td> 
      <td>John Resig</td> 
      <td>Plugins</td> 
     </tr> 
     <tr> 
      <td>Sep 4</td> 
      <td>The Official jQuery Podcast Has a New Home</td> 
      <td>Ralph Whitbeck</td> 
      <td>Documentation</td> 
     </tr> 
     <tr> 
      <td>Aug 24</td> 
      <td>jQuery Conference 2010: Boston</td> 
      <td>Ralph Whitbeck</td> 
      <td>Conferences</td> 
     </tr> 
     <tr> 
      <td>Aug 13</td> 
      <td>The jQuery Project is Proud to Announce the jQuery Mobile Project</td> 
      <td>Ralph Whitbeck</td> 
      <td>Plugins</td> 
     </tr> 
     <tr> 
      <td>Jun 14</td> 
      <td>Seattle jQuery Open Space and Hack Attack with John Resig</td> 
      <td>Rey Bango</td> 
      <td>Conferences</td> 
     </tr> 
     <tr> 
      <td>Mar 16</td> 
      <td>Microsoft to Expand its Collaboration with the jQuery Community</td> 
      <td>John Resig</td> 
      <td>Miscellaneous</td> 
     </tr> 
     <tr> 
      <td>Mar 15</td> 
      <td>jQuery Conference 2010: San Francisco Bay Area</td> 
      <td>Mike Hostetler</td> 
      <td>Conferences</td> 
     </tr> 
     <tr> 
      <td>Jan 14</td> 
      <td>jQuery 1.4 Released</td> 
      <td>John Resig</td> 
      <td>Releases</td> 
     </tr> 
     <tr> 
      <td>Jan 8</td> 
      <td>14 Days of jQuery and the New API Browser</td> 
      <td>John Resig</td> 
      <td>Documentation</td> 
     </tr> 
    </tbody> 

    <tbody> 
     <tr> 
      <th colspan="4">2005</th> 
     </tr> 
     <tr> 
      <td>Dec 17</td> 
      <td>JSON and RSS</td> 
      <td>John Resig</td> 
      <td>Documentation</td> 
     </tr> 
     <tr> 
      <td>Dec 14</td> 
      <td>Google Homepage API</td> 
      <td>John Resig</td> 
      <td>Miscellaneous</td> 
     </tr> 
     <tr> 
      <td>Dec 13</td> 
      <td>XPath and CSS Selectors</td> 
      <td>John Resig</td> 
      <td>Miscellaneous</td> 
     </tr> 
     <tr> 
      <td>Dec 12</td> 
      <td>Sparklines with JavaScript and Canvas</td> 
      <td>John Resig</td> 
      <td>Miscellaneous</td> 
     </tr> 
    </tbody> 

</table> 

感謝

Answer 1

在你的榜樣，matches[3] == "3"。因此parseInt(matches[3], 10);會將「3」轉換爲整數3（基數10 =十進制）。