I am learning jQuery, while reading book, there is a code, where you are making custom selector. Here is the code
(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);
and here it is calling
$(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();
});
I know that .filter() runs for each sub element. suppose that if my tbody element has 4 tr(rows), then .filter runs for each tr(implicit iteration). Now when call .filter(':group(3)'), then i notice that the parameters that passes to :group function are.
First time it become
group: function(element, index, matches, set)
element is tr , index is 0, mathces become [":group(3)", "group", "", "3"] and set become [tr, tr, tr, tr, tr]
Now i undrstand set, that each tbody tag has number of tr, that become set array. But please also tell me that how parseInt(matches[3], 10) is working?
I want to ask how jQuery made matches array. I just write :group(3). How matches value is setting to these values in the parameter list?
Here is the snippet of html
<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 & 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>
Thanks
