jQuery自定义选择器代码

Question

我正在学习jQuery，在阅读书籍时，有一个代码，您正在制作自定义选择器。下面是代码

(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); 

，并在这里呼吁

$(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（）运行对每个子元素。假设如果我的tbody元素有4个tr（行），那么对每个tr运行.filter（隐式迭代）。 现在，当调用.filter（'：group（3）'）时，我注意到传递给：group函数的参数是。

首次成为

组：功能（元件，索引，火柴，设置）

元件是TR，索引是0，符合项目成为[“：组（3）“，”组“，”“，”3“]和组变成[tr，tr，tr，tr，tr]

现在，我设置了一组，每个tbody标签都有tr的数量，这成为了set数组。但是请告诉我，parseInt（匹配[3]，10）如何工作？

我想问问jQuery如何制作匹配数组。我只写：组（3）。如何将匹配值设置为参数列表中的这些值？

这里是HTML的代码片段

<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> 

感谢

Answer 1

在你的榜样，matches[3] == "3"。因此parseInt(matches[3], 10);会将“3”转换为整数3（基数10 =十进制）。