muzik

There is already several Categories Widget in WordPress Plugins Database,such as Breukie’s Categories Widget.But when I upgrade my site to WordPress2.8,it doesn’t work any more.So I wrote this.It displays your categories using the wp_list_categories/wp_dropdown_categories function, utilizes parameters for this function.You can set up one or more this widget in your sidebar(s).
<a href="http://phonedelta.com/" rel="nofollow ugc">Live Demo</a>

Alpha’s Categories Widget

Enhanced Categories Widget,Compatible up to WordPress 2.8.

robfelty

Collapsing Categories creates an expandable list of categories and 
subcategories. It can also expand to show posts. The primary usage is as a 
widget, but you can also use the code in your theme manually if you wish (see 
installation instructions)
<h3>Options</h3>
Options can be set 
from the block panel. If you wish to insert the code into your theme manually 
instead of using a widget, you can use the following options. These options 
can be given to the <code>collapsCat()</code> function either as an array or in query 
style, in the same manner as the <code>wp_list_categories</code> function.
<pre><code>$defaults=array(
 'showPostCount' => true,
 'inExclude' => 'exclude',
 'inExcludeCats' => '',
 'showPosts' => true, 
 'showPages' => false,
 'linkToCat' => true,
 'olderThan' => 0,
 'excludeAll' => '0',
 'catSortOrder' => 'ASC',
 'catSort' => 'catName',
 'postSortOrder' => 'ASC',
 'postSort' => 'postTitle',
 'expand' => '0',
 'defaultExpand' => '',
 'postTitleLength' => 0,
 'accordion' => 0,
 'catfeed' => 'none',
 'taxonomy' => 'category',
 'showPostDate' => false,
 'postDateAppend' => 'after',
 'postDateFormat' => 'm/d',
 'useCookies' => true,
 'showTopLevel' => true,
 'postsBeforeCats' => false,
 'expandCatPost' => true,
 'debug'=>'0'
);
</code></pre>
<ul>
<li>inExclude
<ul>
<li>Whether to include or exclude certain categories
<ul>
<li>‘exclude’ (default) </li>
<li>‘include’</li>
</ul>
</li>
</ul>
</li>
<li>inExcludeCats
<ul>
<li>The categories which should be included or excluded</li>
</ul>
</li>
<li>showPages
<ul>
<li>Whether or not to include pages as well as posts. Default if false</li>
</ul>
</li>
<li>linkToCat
<ul>
<li>1 (true), clicking on a category title will link to the category archive (default)</li>
<li>0 (false), clicking on a category title expands and collapses </li>
</ul>
</li>
<li>catSort
<ul>
<li>How to sort the categorys. Possible values:
<ul>
<li>‘catName’ the title of the category (default)</li>
<li>‘catId’ the Id of the category</li>
<li>‘catSlug’ the url of the category</li>
<li>‘catCount’ the number of posts in the category</li>
<li>‘catOrder’ custom order specified in the categorys settings</li>
</ul>
</li>
</ul>
</li>
<li>catSortOrder
<ul>
<li>Whether categories should be sorted in normal or reverse 
order. Possible values:
<ul>
<li>‘ASC’ normal order (a-z 0-9) (default)</li>
<li>‘DESC’ reverse order (z-a 9-0) </li>
</ul>
</li>
</ul>
</li>
<li>postSort
<ul>
<li>How to sort the posts. Possible values:
<ul>
<li>‘postDate’ the date of the post (default)</li>
<li>‘postId’ the Id of the post</li>
<li>‘postTitle’ the title of the post</li>
<li>‘postComment’ the number of comments on the post</li>
<li>‘postOrder’ sort by menu order</li>
</ul>
</li>
</ul>
</li>
<li>postSortOrder
<ul>
<li>Whether post should be sorted in normal or reverse 
order. Possible values:
<ul>
<li>‘ASC’ normal order (a-z 0-9) (default)</li>
<li>‘DESC’ reverse order (z-a 9-0) </li>
</ul>
</li>
</ul>
</li>
<li>expand
<ul>
<li>The symbols to be used to mark expanding and collapsing. Possible values:
<ul>
<li>‘0’ Triangles (default)</li>
<li>‘1’ + –</li>
<li>‘2’ [+] [-]</li>
<li>‘3’ images (you can upload your own if you wish)</li>
<li>‘4’ custom symbols</li>
</ul>
</li>
</ul>
</li>
<li>customExpand
<ul>
<li>If you have selected ‘4’ for the expand option, this character will be 
used to mark expandable link categories</li>
</ul>
</li>
<li>customCollapse
<ul>
<li>If you have selected ‘4’ for the expand option, this character will be 
used to mark collapsible link categories</li>
</ul>
</li>
<li>postTitleLength
<ul>
<li>Truncate post titles to this number of characters (default: 0 = don’t 
truncate)</li>
</ul>
</li>
<li>accordion
<ul>
<li>When set to true, expanding one category closes all others at that level</li>
</ul>
</li>
<li>catfeed
<ul>
<li>Whether to add a link to the rss feed for a category. Possible values:
<ul>
<li>‘none’ (default)</li>
<li>‘text’ shows RSS</li>
<li>‘image’ shows an RSS icon</li>
</ul>
</li>
</ul>
</li>
<li>taxonomy
<ul>
<li>Type of taxonmy to display. Possible values:
<ul>
<li>‘category’ (default)</li>
<li>‘link_category’</li>
<li>‘post_tag’</li>
<li>‘both’ (categories and tags)</li>
<li>any other registered taxononmy (e.g. recipe press uses recipe-categories)</li>
</ul>
</li>
</ul>
</li>
<li>showPostDate
<ul>
<li>When true, show the date of each post</li>
</ul>
</li>
<li>postDateAppend
<ul>
<li>Show the date before or after the post title. Possible values:
<ul>
<li>‘after’ (default)</li>
<li>‘before’</li>
</ul>
</li>
</ul>
</li>
<li>postDateFormat
<ul>
<li>What format the post date is in. This uses the standard php date 
formatting codes</li>
</ul>
</li>
<li>useCookies
<ul>
<li>When true, expanding and collapsing of categories is remembered for each 
visitor. When false, categories are always display collapsed (unless 
explicitly set to auto-expand). Possible values:
<ul>
<li>1 (true) (default)</li>
<li>0 (false)</li>
</ul>
</li>
</ul>
</li>
<li>showTopLevel
<ul>
<li>When set to false, the top level category will not be shown. This could 
be useful if you only want to show subcategories from one particular 
top-level category
<ul>
<li>1 (true) (default)</li>
<li>0 (false)</li>
</ul>
</li>
</ul>
</li>
<li>postsBeforeCats
<ul>
<li>When set to true, posts in category X will be ordered before 
subcategories of category X
<ul>
<li>1 (true)</li>
<li>0 (false) (default)</li>
</ul>
</li>
</ul>
</li>
<li>expandCatPost
<ul>
<li>When set to true, any category to which a post is assigned will 
automatically be expanded on a single post page.
<ul>
<li>1 (true) (default)</li>
<li>0 (false)</li>
</ul>
</li>
</ul>
</li>
<li>showEmptyCat
<ul>
<li>When set to true, empty categories are shown
<ul>
<li>0 (false) (default)</li>
<li>1 (true) </li>
</ul>
</li>
</ul>
</li>
<li>debug
<ul>
<li>When set to true, extra debugging information will be displayed in the 
underlying code of your page (but not visible from the browser). Use 
this option if you are having problems</li>
</ul>
</li>
</ul>
<h4>Examples</h4>
<pre><code>collapsCat('catSort=ASC&expand=3&inExcludeCats=general,uncategorized')
</code></pre>
This will produce a list with: 
* categories shown in alphabetical order 
* using images to mark collapsing and expanding 
* exclude posts from the categories general and uncategorized
<pre><code>`
</code></pre>
<?php 
 echo '
<ul>‘ . “\n”; 
 if (function_exists(‘collapsCat’)) { 
 collapsCat(array( 
 ‘postSort’ => ‘postDate’, 
 ‘postSortOrder’ => ‘DESC’, 
 ) ); 
 } else { 
 wp_get_categories(‘your_options_here’); 
 } 
 echo “</ul>
\n”; 
 ?> 
 `
<h3>Demo</h3>
I use this plugin in my blog at http://robfelty.com
<h3>CAVEAT</h3>
Currently this plugin relies on Javascript to expand and collapse the links. 
If a user’s browser doesn’t support javascript they won’t see the links to the 
posts, but the links to the categories will still work (which is the default 
behavior in wordpress anyways)

Collapsing Categories


	doesn't work with WP 4.9.1
	the code is terrible: it adds a big, ugly javascript in page with the widget html content. Never seen such an horror before.


Amateur work, avoid it.

doesn't work, bad coding

Adds a widget which uses Javascript to dynamically expand or collapse the set of posts for each category.

Alpha’s Categories Widget vs Collapsing Categories