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As with many others who are now viewing this post, I have been reading various blogs, forums, and discussion groups to learn and improve my wordpress skills. Over the past 12 months I have been on a mission to substitute my use of plugins by adding code to my functions.php file instead. While I completely agree that plugins are very useful in many situations my experience proved that in 90% of usage cases although a plugin might exist, actually utilizing it could create unnecessary complications and compatibility issues. Additionally in a great deal of cases such plugins added menus and other admin elements which I don't want or need.

More often than not I have found that by analyzing the code of plugins I was able to strip out the piece of code I wanted and hard code it into my functions.php. This provided me with the exact functionality I needed without having to include unnecessary elements.

So, the purpose of this post is my attempt to engage you, the reader/admin/developer, to share with me and other here any code bits which you find useful and have added to your theme's function.php file to extend or enhance WordPress without utilizing a plugin.

When you submit a response here please kindly give each code bit a title, let us know if with what version of wordpress you know its compatible with, include whatever description you feel best describes its function and (if applicable) include a link to the original plugin or source where you found the information.

I am looking forward to all your responses and will of course continually add my own new finds whenever I find them.

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9  
Considering the first 5 answers were by the OP and the question seems more geared at collecting an array of responses rather than a single, definitive answer, this should be a community wiki. –  EAMann Sep 9 '10 at 14:43
13  
All answers not related to a theme should be removed. This thread is a good example for bad coding practices. –  toscho Jun 13 '11 at 12:09
14  
I think it'd be better to encourage people to create a custom functionality plugin instead of using their theme's functions.php –  Ian Dunn Jan 16 '12 at 18:49
2  
@NetConstructor.com The pure number of page views is not an indicator for quality. We should encourage specific questions with specific answers and good coding practices. This thread is the opposite. –  toscho Feb 22 '12 at 2:44
5  
@NetConstructor.com Discuss it on Meta where people can see your arguments better. :) –  toscho Feb 24 '12 at 17:10
show 20 more comments

closed as not constructive by Rarst Feb 15 '12 at 12:44

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.If this question can be reworded to fit the rules in the help center, please edit the question.

108 Answers

Customize the order of the admin menu

tested on: Wordpress 3.0.1

This code will allow you to reorganize the order of elements in the admin menu. All that you need to do is click on an existing link in the admin menu and copy everything before the /wp-admin/ URL. The order below represents the order the new admin menu will have.

// CUSTOMIZE ADMIN MENU ORDER
   function custom_menu_order($menu_ord) {
       if (!$menu_ord) return true;
       return array(
        'index.php', // this represents the dashboard link
        'edit.php?post_type=events', // this is a custom post type menu
        'edit.php?post_type=news', 
        'edit.php?post_type=articles', 
        'edit.php?post_type=faqs', 
        'edit.php?post_type=mentors',
        'edit.php?post_type=testimonials',
        'edit.php?post_type=services',
        'edit.php?post_type=page', // this is the default page menu
        'edit.php', // this is the default POST admin menu 
    );
   }
   add_filter('custom_menu_order', 'custom_menu_order');
   add_filter('menu_order', 'custom_menu_order');
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3  
@kaiser documented here codex.wordpress.org/Plugin_API/Filter_Reference/… –  Manny Fleurmond Aug 18 '12 at 17:08
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Remove Default Wordpress Meta Boxes

Tested on: Wordpress 3.0.1

This code will allow you to remove specific Meta Boxes which wordpress adds by default to the default Add/Edit Post and Add/Edit Page screens.

// REMOVE META BOXES FROM DEFAULT POSTS SCREEN
   function remove_default_post_screen_metaboxes() {
 remove_meta_box( 'postcustom','post','normal' ); // Custom Fields Metabox
 remove_meta_box( 'postexcerpt','post','normal' ); // Excerpt Metabox
 remove_meta_box( 'commentstatusdiv','post','normal' ); // Comments Metabox
 remove_meta_box( 'trackbacksdiv','post','normal' ); // Talkback Metabox
 remove_meta_box( 'slugdiv','post','normal' ); // Slug Metabox
 remove_meta_box( 'authordiv','post','normal' ); // Author Metabox
 }
   add_action('admin_menu','remove_default_post_screen_metaboxes');


// REMOVE META BOXES FROM DEFAULT PAGES SCREEN
   function remove_default_page_screen_metaboxes() {
 remove_meta_box( 'postcustom','page','normal' ); // Custom Fields Metabox
 remove_meta_box( 'postexcerpt','page','normal' ); // Excerpt Metabox
 remove_meta_box( 'commentstatusdiv','page','normal' ); // Comments Metabox
 remove_meta_box( 'trackbacksdiv','page','normal' ); // Talkback Metabox
 remove_meta_box( 'slugdiv','page','normal' ); // Slug Metabox
 remove_meta_box( 'authordiv','page','normal' ); // Author Metabox
 }
   add_action('admin_menu','remove_default_page_screen_metaboxes');
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8  
You may have a typo in the above code, shouldn't the second function set the type to page, and not post like the first? –  t31os Nov 26 '10 at 22:24
4  
According to this wordpress.stackexchange.com/questions/34030/… I wouldn't hide the slugdiv this way, but use this gist.github.com/1863830 instead –  Cor van Noorloos Feb 19 '12 at 13:25
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Reposition the WYSIWYG Editor through JQUERY

Tested on: Wordpress 3.0.1

This code will allow you to remove specific meta boxes which wordpress adds by default to the POST and PAGES screens.

// REPOSITION WYSIWYG EDITOR THROUGH JQUERY
   add_action('admin_head','admin_head_hook');
   function admin_head_hook() {
 ?><style type="text/css">
  #postdiv.postarea, #postdivrich.postarea { margin:0; }
  #post-status-info { line-height:1.4em; font-size:13px; }
  .custom-wysiwyg-editor-container { margin:2px 6px 6px 6px; }
  #ed_toolbar { display:none; }
  #postdiv #ed_toolbar, #postdivrich #ed_toolbar { display:block; }
 </style><?php
   }

   add_action('admin_footer','admin_footer_hook');
   function admin_footer_hook() {
 ?><script type="text/javascript">
  jQuery('#postdiv, #postdivrich').prependTo('.custom-wysiwyg-editor-container');
 </script><?php
   }
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Automatically close missing tags from the WYSIWYG editor

Tested on: Wordpress 3.0.1

This code will automatically close any missing tags when using the WYSIWYG editor.

// AUTOMATICALLY CLEAN UP HTML WYSIWYG EDITOR BY CLOSING MISSING TAGS
   function clean_bad_content($bPrint = false) {
 global $post;
 $szPostContent  = $post->post_content;
 $szRemoveFilter = array("~<p[^>]*>\s?</p>~", "~<a[^>]*>\s?</a>~", "~<font[^>]*>~", "~<\/font>~", "~style\=\"[^\"]*\"~", "~<span[^>]*>\s?</span>~");
 $szPostContent  = preg_replace($szRemoveFilter, '', $szPostContent);
 $szPostContent  = apply_filters('the_content', $szPostContent);
 if ($bPrint == false) return $szPostContent; 
 else echo $szPostContent;
   }
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Remove Update Notification for all users except ADMIN User

Tested on: Wordpress 3.0.1

This code will ensures that no users other than "admin" are notified by wordpress when updates are available..

// REMOVE THE WORDPRESS UPDATE NOTIFICATION FOR ALL USERS EXCEPT SYSADMIN
   global $user_login;
   get_currentuserinfo();
   if ($user_login !== "admin") { // change admin to the username that gets the updates
    add_action( 'init', create_function( '$a', "remove_action( 'init', 'wp_version_check' );" ), 2 );
    add_filter( 'pre_option_update_core', create_function( '$a', "return null;" ) );
   }

Changed version to only show update notification for admin users (as opposed to just the user 'admin'):

// REMOVE THE WORDPRESS UPDATE NOTIFICATION FOR ALL USERS EXCEPT SYSADMIN
       global $user_login;
       get_currentuserinfo();
       if (!current_user_can('update_plugins')) { // checks to see if current user can update plugins 
        add_action( 'init', create_function( '$a', "remove_action( 'init', 'wp_version_check' );" ), 2 );
        add_filter( 'pre_option_update_core', create_function( '$a', "return null;" ) );
       }
share|improve this answer
5  
This is far less than ideal. It will only work if the admin's login is still the default 'admin', which it shoudln't be for security reasons. Instead you should check for a specific capability that you want people to have to see messages. –  Jeremy Clarke Sep 11 '10 at 20:28
1  
I.e. if (!current_user_can('manage_options')) {...add_filter...} -- Sorry about double comment, I forgot that hitting enter submits comments) –  Jeremy Clarke Sep 11 '10 at 20:29
2  
so: if (!current_user_can('update_plugins')) {/*REMOVE MESSAGES*/} –  Jeremy Clarke Sep 12 '10 at 14:01
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Enable Numeric Pagination

Tested on: Wordpress 3.0.1

/* Numeric Pagination ********************************************/

function numeric_pagination ($pageCount = 9, $query = null) {

 if ($query == null) {
  global $wp_query;
  $query = $wp_query;
 }

 if ($query->max_num_pages <= 1) {
  return;
 }

 $pageStart = 1;
 $paged = $query->query_vars['paged'];

 // set current page if on the first page
 if ($paged == null) {
  $paged = 1;
 }

 // work out if page start is halfway through the current visible pages and if so move it accordingly
 if ($paged > floor($pageCount / 2)) {
  $pageStart = $paged - floor($pageCount / 2);
 }

 if ($pageStart < 1) {
  $pageStart = 1;
 }

 // make sure page start is
 if ($pageStart + $pageCount > $query->max_num_pages) {
  $pageCount = $query->max_num_pages - $pageStart;
 }

?>
 <div id="archive_pagination">
<?php
 if ($paged != 1) {
?>
 <a href="<?php echo get_pagenum_link(1); ?>" class="numbered page-number-first"><span>&lsaquo; <?php _e('<< First', 'global'); ?></span></a>
<?php
 }
 // first page is not visible...
 if ($pageStart > 1) {
  //echo 'previous';
 }
 for ($p = $pageStart; $p <= $pageStart + $pageCount; $p ++) {
  if ($p == $paged) {
?>
  <span class="numbered page-number-<?php echo $p; ?> current-numeric-page"><?php echo $p; ?></span>
<?php } else { ?>
  <a href="<?php echo get_pagenum_link($p); ?>" class="numbered page-number-<?php echo $p; ?>"><span><?php echo $p; ?></span></a>

<?php
  }
 }
 // last page is not visible
 if ($pageStart + $pageCount < $query->max_num_pages) {
  //echo "last";
 }
 if ($paged != $query->max_num_pages) {
?>
  <a href="<?php echo get_pagenum_link($query->max_num_pages); ?>" class="numbered page-number-last"><span><?php _e('>> Last', 'global'); ?> &rsaquo;</span></a>
<?php } ?>

 </div>
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10  
There's a function in WordPress for doing numeric pagination already, see codex.wordpress.org/Function_Reference/paginate_links –  t31os Nov 11 '10 at 17:09
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Automatically Add Dynamic Titles to Public Pages

Tested on: Wordpress 3.0.1

Utilizing the code below will automatically create dynamic page titles based upon the pages/posts being viewed publicly.

/* Dynamic Titles **/
// This sets your <title> depending on what page you're on, for better formatting and for SEO
// You need to set the variable $longd to some custom text at the beginning of the function
function dynamictitles() {
$longd = __('Enter your longdescription here.', 'texdomainstring');
    if ( is_single() ) {
      wp_title('');
      echo ' | '.get_bloginfo('name');

} else if ( is_page() || is_paged() ) {
      bloginfo('name');
      wp_title('|');

} else if ( is_author() ) {
      bloginfo('name');
      wp_title(' | '.__('Author', 'texdomainstring'));

} else if ( is_category() ) {
      bloginfo('name');
      wp_title(' | '.__('Archive for', 'texdomainstring'));

} else if ( is_tag() ) {
      echo get_bloginfo('name').' | '.__('Tag archive for', 'texdomainstring');
      wp_title('');

} else if ( is_archive() ) {
      echo get_bloginfo('name').' | '.__('Archive for', 'texdomainstring');
      wp_title('');

} else if ( is_search() ) {
      echo get_bloginfo('name').' | '.__('Search Results', 'texdomainstring');
} else if ( is_404() ) {
      echo get_bloginfo('name').' | '.__('404 Error (Page Not Found)', 'texdomainstring');

} else if ( is_home() ) {
      echo get_bloginfo('name').' | '.get_bloginfo('description');

} else {
      echo get_bloginfo('name').' | '.($blog_longd);
}
}
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Auto Extract the First Image from the Post Content

Tested on: Wordpress 3.0.1

This code will automatically extract the first image associated with a post and allow you to display/use it by calling the getImage function.

// AUTOMATICALLY EXTRACT THE FIRST IMAGE FROM THE POST 
function getImage($num) {
    global $more;
    $more = 1;
    $link = get_permalink();
    $content = get_the_content();
    $count = substr_count($content, '<img');
    $start = 0;
    for($i=1;$i<=$count;$i++) {
        $imgBeg = strpos($content, '<img', $start);
        $post = substr($content, $imgBeg);
        $imgEnd = strpos($post, '>');
        $postOutput = substr($post, 0, $imgEnd+1);
        $postOutput = preg_replace('/width="([0-9]*)" height="([0-9]*)"/', '',$postOutput);;
        $image[$i] = $postOutput;
        $start=$imgEnd+1;
    }
    if(stristr($image[$num],'<img')) { echo '<a href="'.$link.'">'.$image[$num]."</a>"; }
    $more = 0;
}
share|improve this answer
6  
Nice, but get_the_image does a very good job with this as well. wordpress.org/extend/plugins/get-the-image –  artlung Sep 15 '10 at 15:56
3  
What does it do differently than the get_the_image script? –  matt Dec 5 '10 at 4:47
1  
@matt -- In wordpress there are different ways that images can be added to posts and i think the get_the_image script just looks at one of those. This checks to see if there is a featured image and uses that one first if available, next I think it checks for the first image added to the post content and if that is not found it checks the media gallery for the image with the highest sort order (at least thats how I remember the order going). –  NetConstructor.com Feb 22 '11 at 20:01
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Modify the Login Logo & Image URL Link

Tested on: WordPress 3.0.1

This code will allow you to easily modify the WordPress Login page Logo as well as the href link and title text of this logo.

add_filter( 'login_headerurl', 'namespace_login_headerurl' );
/**
 * Replaces the login header logo URL
 *
 * @param $url
 */
function namespace_login_headerurl( $url ) {
    $url = home_url( '/' );
    return $url;
}

add_filter( 'login_headertitle', 'namespace_login_headertitle' );
/**
 * Replaces the login header logo title
 *
 * @param $title
 */
function namespace_login_headertitle( $title ) {
    $title = get_bloginfo( 'name' );
    return $title;
}

add_action( 'login_head', 'namespace_login_style' );
/**
 * Replaces the login header logo
 */
function namespace_login_style() {
    echo '<style>.login h1 a { background-image: url( ' . get_template_directory_uri() . '/images/logo.png ) !important; }</style>';
}

EDIT: If you want to use the site logo to replace the login logo, you can use the following to dynamically pull that information (tested on WP3.5):

function namespace_login_style() {
    if( function_exists('get_custom_header') ){
        $width = get_custom_header()->width;
        $height = get_custom_header()->height;
    } else {
        $width = HEADER_IMAGE_WIDTH;
        $height = HEADER_IMAGE_HEIGHT;
    }
    echo '<style>'.PHP_EOL;
    echo '.login h1 a {'.PHP_EOL; 
    echo '  background-image: url( '; header_image(); echo ' ) !important; '.PHP_EOL;
    echo '  width: '.$width.'px !important;'.PHP_EOL;
    echo '  height: '.$height.'px !important;'.PHP_EOL;
    echo '  background-size: '.$width.'px '.$height.'px !important;'.PHP_EOL;
    echo '}'.PHP_EOL;
    echo '</style>'.PHP_EOL;
}
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Enable Hidden Admin Feature displaying ALL Site Settings

Tested on: Wordpress 3.1 RC3

This little piece of code does something pretty cool. It will add an additional option to your settings menu with a link to "all settings" which will show you a complete list of all the settings you have within your database related to your wordpress site. The code below will only made this link visible to an admin user and hide it for all other users.

// CUSTOM ADMIN MENU LINK FOR ALL SETTINGS
   function all_settings_link() {
    add_options_page(__('All Settings'), __('All Settings'), 'administrator', 'options.php');
   }
   add_action('admin_menu', 'all_settings_link');
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Set a maximum number of post revisions to avoid DB bloat.

Tested on: Wordpress 3.0.1

Default is infinite, this will set it to only remember last 5 edits:

/**
 * Set the post revisions unless the constant was set in wp-config.php
 */
if (!defined('WP_POST_REVISIONS')) define('WP_POST_REVISIONS', 5);

FWIW there are a ton of great ideas for CONSTANTS that can be set on the Codex page Editing wp-config.php.

share|improve this answer
1  
personally I prefer 10. I know it's double but always when I need a revision it's always older then 5 –  janw Sep 4 '12 at 12:04
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Function to Disable RSS Feeds

Tested on: Wordpress 3.0.1

You can disable RSS feeds If you want to maintain your Wordpress based website as static.

You can Use this function :

function fb_disable_feed() {
wp_die( __('No feed available,please visit our <a href="'. get_bloginfo('url') .'">homepage</a>!') );
}

add_action('do_feed', 'fb_disable_feed', 1);
add_action('do_feed_rdf', 'fb_disable_feed', 1);
add_action('do_feed_rss', 'fb_disable_feed', 1);
add_action('do_feed_rss2', 'fb_disable_feed', 1);
add_action('do_feed_atom', 'fb_disable_feed', 1);
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Function to change the length of Exerpt

Tested on: Wordpress 3.0.1

By default all excerpts are capped at 55 words. Utilizing the code below you can override this default settings:

function new_excerpt_length($length) { 
    return 100;
}

add_filter('excerpt_length', 'new_excerpt_length');

This example changes the excerpt length to 100 words, but you can use the same method to change it to any value.

share|improve this answer
3  
@NetConstructor.com This function (and the excerpt_length hook) cap by words. –  EAMann Sep 15 '10 at 17:53
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Remove XML-RPC when not in use for performance boost

Tested on: Wordpress 3.0.1

WordPress uses a CURL operation to test for SSL capability for XML-RPC. If you're using XML-RPC but not using, then you can remove the filter. This is a small performance boost (since basically WP does a cURL GET on the https url and either 1) gets a denied message, or 2) times out, and it can take upwards of 5 seconds), but in our case it actually prevented a gateway timeout where a proxy was timing out before the cURL GET was timing out rendering XML-RPC unusable.

// Prevents WordPress from testing ssl capability on domain.com/xmlrpc.php?rsd
remove_filter('atom_service_url','atom_service_url_filter');
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Get the Users Real IP Address whenever possible

Tested on: Wordpress 3.0.1

If you're using a proxy or load balancer, adding this to your wp-config.php file or functions.php

// Gets the user's real IP address

$_SERVER['REMOTE_ADDR'] = getRealIpAddress();
function getRealIpAddress( $validate = true ) {
    if ( isset($_SERVER['HTTP_X_FORWARDED_FOR']) && !empty($_SERVER['HTTP_X_FORWARDED_FOR']) ) {
        $ips = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
        $ip = trim($ips[count($ips) - 1]);
    } elseif ( isset($_SERVER['HTTP_X_REAL_IP']) && !empty($_SERVER['HTTP_X_REAL_IP']) ) {
        $ip = $_SERVER['HTTP_X_REAL_IP'];
    } elseif ( isset($_SERVER['HTTP_CLIENT_IP']) && !empty($_SERVER['HTTP_CLIENT_IP']) ) {
        $ip = $_SERVER['HTTP_CLIENT_IP'];
    } else {
        $ip = $_SERVER['REMOTE_ADDR'];
    }

    if ( $validate && function_exists('filter_var') &&  filter_var($ip, FILTER_VALIDATE_IP, array('flags' => FILTER_FLAG_IPV4, FILTER_FLAG_NO_PRIV_RANGE, FILTER_FLAG_NO_RES_RANGE)) )
        return $ip;
    elseif ( $validate )
        return long2ip(ip2long($ip));

    return $ip;
}
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1  
what does this do exactly? –  NetConstructor.com Sep 14 '10 at 2:21
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Remove pings to your own blog

Tested on: Wordpress 3.0.1

//remove pings to self
function no_self_ping( &$links ) {
    $home = get_option( 'home' );
    foreach ( $links as $l => $link )
        if ( 0 === strpos( $link, $home ) )
            unset($links[$l]);
}
add_action( 'pre_ping', 'no_self_ping' );
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Auto Include Google Analytics Code

Tested on: Wordpress 3.1 RC3

I've been using this script on all of my sites since WordPress 2.3.0 ... it just adds the standard Google tracking scripts to the footer.

// Add Google Analytics Tracking Code
function add_google_analytics() {
?>
<script type="text/javascript">
    var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
    document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
</script>
<script type="text/javascript">
    try {
        var pageTracker = _gat._getTracker("UA-XXXXXXX-X");
        pageTracker._trackPageview();
    } catch(err) {}</script>
<?php
}

add_action('wp_footer', 'add_google_analytics');

Just be sure to replace UA-XXXXXXX-X with your own Google tracking code...

share|improve this answer
1  
Not sure about adding campaign tracking variables only because I haven't had a need for that yet. But to add the same scripts to admin pages, you'd just use add_action('admin_footer', 'add_google_analytics'); to hook on to the footer of admin pages. –  EAMann Sep 17 '10 at 13:08
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Remove "Wordpress" to "WordPress" filter

Tested on: Wordpress 3.0.1

There was a filter added with WordPress version 3.0 that automatically converts all instances of "Wordpress" (no capital P) to "WordPress" (with a capital P) in post content, post titles, and comment text. Some people see this as intrusive, I just have a need to mis-case WordPress from time to time and found the filter somewhat annoying.

// Remove annoying P filter
if(function_exists('capital_P_dangit')) {
    foreach ( array( 'the_content', 'the_title' ) as $filter ) 
        remove_filter( $filter, 'capital_P_dangit', 11 ); 

    remove_filter('comment_text', 'capital_P_dangit', 31 );
}
share|improve this answer
5  
In WordPress 3.0.1, this filter is added with priority 11, so you need to add 11 as the third parameter to remove it. –  Jan Fabry Nov 5 '10 at 23:01
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Post Word Count

Tested on: Wordpress 3.0.1

(Originally extracted from the Post Word Count plug-in by Nick Momrick)

Adds a count of total published words to the bottom of the "Right Now" box on the admin dashboard. Useful if you're using your blog as an outlet for something like NaNoWriMo or if you just want to keep track of how prolific your blogging skills have become.

function post_word_count() {
    $count = 0;
    $posts = get_posts( array(
        'numberposts' => -1,
        'post_type' => array( 'post', 'page' )
    ));
    foreach( $posts as $post ) {
        $count += str_word_count( strip_tags( get_post_field( 'post_content', $post->ID )));
    }
    $num =  number_format_i18n( $count );
    // This block will add your word count to the stats portion of the Right Now box
    $text = _n( 'Word', 'Words', $num );
    echo "<tr><td class='first b'>{$num}</td><td class='t'>{$text}</td></tr>";
    // This line will add your word count to the bottom of the Right Now box.
    echo '<p>This blog contains a total of <strong>' . $num . '</strong> published words!</p>';
}

// add to Content Stats table
add_action( 'right_now_content_table_end', 'post_word_count');
// add to bottom of Activity Box
add_action('activity_box_end', 'post_word_count');

Kudos to Rarst for the query-free cleanup of the code!

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Display DB Queries, Time Spent and Memory Consumption

Tested on: Wordpress 3.0.1

function performance( $visible = false ) {

    $stat = sprintf(  '%d queries in %.3f seconds, using %.2fMB memory',
        get_num_queries(),
        timer_stop( 0, 3 ),
        memory_get_peak_usage() / 1024 / 1024
        );

    echo $visible ? $stat : "<!-- {$stat} -->" ;
}

Then this code below the code above which will automatically insert the code above into the footer of your public website (make sure your theme is calling wp_footer):

add_action( 'wp_footer', 'performance', 20 );

Can be called multiple times.

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Loading jQuery from the Google CDN

Tested on: Wordpress 3.0.1

// even more smart jquery inclusion :)
add_action( 'init', 'jquery_register' );

// register from google and for footer
function jquery_register() {

if ( !is_admin() ) {

    wp_deregister_script( 'jquery' );
    wp_register_script( 'jquery', ( 'https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js' ), false, null, true );
    wp_enqueue_script( 'jquery' );
}
}

Remove the WordPress Version Info for Security

Tested on: Wordpress 3.0.1

// remove version info from head and feeds
function complete_version_removal() {
    return '';
}
add_filter('the_generator', 'complete_version_removal');

Add Spam & Delete Links to Comments on Front End

Tested on: Wordpress 3.0.1

This makes it way easier to manage comments from the front end by adding spam and delete links.**

// spam & delete links for all versions of wordpress
function delete_comment_link($id) {
    if (current_user_can('edit_post')) {
        echo '| <a href="'.get_bloginfo('wpurl').'/wp-admin/comment.php?action=cdc&c='.$id.'">del</a> ';
        echo '| <a href="'.get_bloginfo('wpurl').'/wp-admin/comment.php?action=cdc&dt=spam&c='.$id.'">spam</a>';
    }
}

Delay the public posting to RSS Feed

Tested on: Wordpress 3.0.1

Finally, I like to delay posting to my RSS feeds for 10-15 minutes because I always find at least a couple errors in my text. Other uses are in case you want content to be exclusive to your site for a day or a week before pushing it out to your RSS readers.

// delay feed update
function publish_later_on_feed($where) {
    global $wpdb;

    if (is_feed()) {
        // timestamp in WP-format
        $now = gmdate('Y-m-d H:i:s');

        // value for wait; + device
        $wait = '10'; // integer

        // http://dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html#function_timestampdiff
        $device = 'MINUTE'; // MINUTE, HOUR, DAY, WEEK, MONTH, YEAR

        // add SQL-sytax to default $where
        $where .= " AND TIMESTAMPDIFF($device, $wpdb->posts.post_date_gmt, '$now') > $wait ";
    }
    return $where;
}
add_filter('posts_where', 'publish_later_on_feed');
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1  
You can also just remove the generator filter: remove_action('wp_head', 'wp_generator'); –  Gipetto Sep 18 '10 at 7:01
24  
ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js expires after just one hour. Always use the full version information like ajax.googleapis.com/ajax/libs/jquery/1.4.3/jquery.min.js – that expires after one year. –  toscho Nov 10 '10 at 14:41
4  
The "Remove the WordPress Version Info for Security" code doesn't actually do anything to increase the security of your site. It doesn't even stop exposure of the WP version being used on your site. –  Joseph Scott Feb 11 '11 at 6:38
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List all constants for information and debugging

Tested on: Wordpress 3.0.1

Will only display the information if you are a logged in user

if ( is_user_logged_in() ) {
    print('<pre>');
    print_r( @get_defined_constants() );
    print('</pre>');
}

Here is version with optional filter that will partially match constant names and values:

function constants($filter = false) {

        $constants = get_defined_constants();

        if( $filter ) {

            $temp = array();

            foreach ( $constants as $key => $constant )
                if( false !== stripos( $key, $filter ) || false !== stripos( $constant, $filter ) )
                    $temp[$key] = $constant;

            $constants = $temp;
        }

        ksort( $constants );
        var_dump( $constants );
    }
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Display Specific Content only for logged in users

Tested on: Wordpress 3.0.1

function content_only4logged_in($content) {

    // ALL LOGGED IN USERS
    if ( is_user_logged_in() &&
            !is_null($content) &&
            !is_feed()
         ) {
        return $content;
    } else {
        $content  = wp_html_excerpt( $content, 80 );
        $content .= ' …';
        $content .= __( 'Sorry, more of this content is only available for logged users.', FB_TEXTDOMAIN );
        return $content;
    }
}
add_action( 'the_content', 'content_only4logged_in' );

more possibilities and informations on the post http://wpengineer.com/2046/control-the-wordpress-content-via-userrights-or-time/

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List all SubCategories

Tested on: Wordpress 3.0.1

$echo = '<ul>' . "\n";
$childcats = get_categories('child_of=' . $cat . '&hide_empty=1');
foreach ($childcats as $childcat) {
    if (1 == $childcat->category_parent) {
        $echo .= "\t" . '<li><a href="' . get_category_link($childcat->cat_ID).'" title="' . $childcat->category_description . '">';
        $echo .= $childcat->cat_name . '</a>';
        $echo .= '</li>' . "\n";
    }
}
$echo .= '</ul>' . "\n";
echo $echo;

also here, more informations and functins in the post http://wpengineer.com/2025/list-all-subcategories/

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1  
Why would you do this when there's a function available specifically for displaying a list of categories..See: codex.wordpress.org/Template_Tags/… –  t31os Nov 11 '10 at 17:06
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Make your Shortlinks Shorter by Removing WWW

Tested on: Wordpress 3.0.1

Make your shortlinks shorter if you include www. in your domain. Via scratch99.com:

add_filter('get_shortlink','sjc_alter_shortlink');
function sjc_alter_shortlink($shortlink) {
    $shortlink = preg_replace('/^(https?:\/\/)?(www\.)/','$1',$shortlink);
    return $shortlink;
}
share|improve this answer
1  
A check should be added to make sure the string "www." is only removed if it is found at the very beginning of the domain part of the original URL. Naively replacing it anywhere in the URL will lead to bugs if it had been used on a domain like owww.com (which actually appears to be running WordPress) :) –  Ingve May 28 '12 at 21:30
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Auto Clean SEO Slugs without removing functionality

Tested on: Wordpress 3.0.1

By adding this code to your functions.php file wordpress will automatically clean up the slug URL title by removing all unnecessary words. I have also extended the capabilities with additional customizations which hide the screen option for slug as well as the metabox. By including the code below any new post you create will automatically get shortened and you will still have the ability to manually edit the slug by clicking on the url under the post title and saving the post.

// AUTOMATICALLY SANITIZE PAGE/POST SEO SLUG FROM SHORT WORDS
   add_filter('name_save_pre', 'seo_slugs', 0);
   function seo_slugs($slug) {
    // We don't want to change an existing slug
 if ($slug) return $slug;
 global $wpdb;
 $seo_slug = strtolower(stripslashes($_POST['post_title']));
 $seo_slug = preg_replace('/&.+?;/', '', $seo_slug); // kill HTML entities
    // kill anything that is not a letter, digit, space or apostrophe
 $seo_slug = preg_replace ("/[^a-zA-Z0-9 \']/", "", $seo_slug);
    // Turn it to an array and strip common words by comparing against c.w. array
 $seo_slug_array = array_diff (split(" ", $seo_slug), seo_slugs_stop_words());
    // Turn the sanitized array into a string
 $seo_slug = join("-", $seo_slug_array);
 return $seo_slug;
   }
   function seo_slugs_stop_words () {
   return array ("a", "able", "about", "above", "abroad", "according", "accordingly", "across", "actually", "adj", "after", "afterwards", "again", "against", "ago", "ahead", "ain't", "all", "allow", "allows", "almost", "alone", "along", "alongside", "already", "also", "although", "always", "am", "amid", "amidst", "among", "amongst", "an", "and", "another", "any", "anybody", "anyhow", "anyone", "anything", "anyway", "anyways", "anywhere", "apart", "appear", "appreciate", "appropriate", "are", "aren't", "around", "as", "a's", "aside", "ask", "asking", "associated", "at", "available", "away", "awfully", "b", "back", "backward", "backwards", "be", "became", "because", "become", "becomes", "becoming", "been", "before", "beforehand", "begin", "behind", "being", "believe", "below", "beside", "besides", "best", "better", "between", "beyond", "both", "brief", "but", "by", "c", "came", "can", "cannot", "cant", "can't", "caption", "cause", "causes", "certain", "certainly", "changes", "clearly", "c'mon", "co", "co.", "com", "come", "comes", "concerning", "consequently", "consider", "considering", "contain", "containing", "contains", "corresponding", "could", "couldn't", "course", "c's", "currently", "d", "dare", "daren't", "definitely", "described", "despite", "did", "didn't", "different", "directly", "do", "does", "doesn't", "doing", "done", "don't", "down", "downwards", "during", "e", "each", "edu", "eg", "eight", "eighty", "either", "else", "elsewhere", "end", "ending", "enough", "entirely", "especially", "et", "etc", "even", "ever", "evermore", "every", "everybody", "everyone", "everything", "everywhere", "ex", "exactly", "example", "except", "f", "fairly", "far", "farther", "few", "fewer", "fifth", "first", "five", "followed", "following", "follows", "for", "forever", "former", "formerly", "forth", "forward", "found", "four", "from", "further", "furthermore", "g", "get", "gets", "getting", "given", "gives", "go", "goes", "going", "gone", "got", "gotten", "greetings", "h", "had", "hadn't", "half", "happens", "hardly", "has", "hasn't", "have", "haven't", "having", "he", "he'd", "he'll", "hello", "help", "hence", "her", "here", "hereafter", "hereby", "herein", "here's", "hereupon", "hers", "herself", "he's", "hi", "him", "himself", "his", "hither", "hopefully", "how", "howbeit", "however", "hundred", "i", "i'd", "ie", "if", "ignored", "i'll", "i'm", "immediate", "in", "inasmuch", "inc", "inc.", "indeed", "indicate", "indicated", "indicates", "inner", "inside", "insofar", "instead", "into", "inward", "is", "isn't", "it", "it'd", "it'll", "its", "it's", "itself", "i've", "j", "just", "k", "keep", "keeps", "kept", "know", "known", "knows", "l", "last", "lately", "later", "latter", "latterly", "least", "less", "lest", "let", "let's", "like", "liked", "likely", "likewise", "little", "look", "looking", "looks", "low", "lower", "ltd", "m", "made", "mainly", "make", "makes", "many", "may", "maybe", "mayn't", "me", "mean", "meantime", "meanwhile", "merely", "might", "mightn't", "mine", "minus", "miss", "more", "moreover", "most", "mostly", "mr", "mrs", "much", "must", "mustn't", "my", "myself", "n", "name", "namely", "nd", "near", "nearly", "necessary", "need", "needn't", "needs", "neither", "never", "neverf", "neverless", "nevertheless", "new", "next", "nine", "ninety", "no", "nobody", "non", "none", "nonetheless", "noone", "no-one", "nor", "normally", "not", "nothing", "notwithstanding", "novel", "now", "nowhere", "o", "obviously", "of", "off", "often", "oh", "ok", "okay", "old", "on", "once", "one", "ones", "one's", "only", "onto", "opposite", "or", "other", "others", "otherwise", "ought", "oughtn't", "our", "ours", "ourselves", "out", "outside", "over", "overall", "own", "p", "particular", "particularly", "past", "per", "perhaps", "placed", "please", "plus", "possible", "presumably", "probably", "provided", "provides", "q", "que", "quite", "qv", "r", "rather", "rd", "re", "really", "reasonably", "recent", "recently", "regarding", "regardless", "regards", "relatively", "respectively", "right", "round", "s", "said", "same", "saw", "say", "saying", "says", "second", "secondly", "see", "seeing", "seem", "seemed", "seeming", "seems", "seen", "self", "selves", "sensible", "sent", "serious", "seriously", "seven", "several", "shall", "shan't", "she", "she'd", "she'll", "she's", "should", "shouldn't", "since", "six", "so", "some", "somebody", "someday", "somehow", "someone", "something", "sometime", "sometimes", "somewhat", "somewhere", "soon", "sorry", "specified", "specify", "specifying", "still", "sub", "such", "sup", "sure", "t", "take", "taken", "taking", "tell", "tends", "th", "than", "thank", "thanks", "thanx", "that", "that'll", "thats", "that's", "that've", "the", "their", "theirs", "them", "themselves", "then", "thence", "there", "thereafter", "thereby", "there'd", "therefore", "therein", "there'll", "there're", "theres", "there's", "thereupon", "there've", "these", "they", "they'd", "they'll", "they're", "they've", "thing", "things", "think", "third", "thirty", "this", "thorough", "thoroughly", "those", "though", "three", "through", "throughout", "thru", "thus", "till", "to", "together", "too", "took", "toward", "towards", "tried", "tries", "truly", "try", "trying", "t's", "twice", "two", "u", "un", "under", "underneath", "undoing", "unfortunately", "unless", "unlike", "unlikely", "until", "unto", "up", "upon", "upwards", "us", "use", "used", "useful", "uses", "using", "usually", "v", "value", "various", "versus", "very", "via", "viz", "vs", "w", "want", "wants", "was", "wasn't", "way", "we", "we'd", "welcome", "well", "we'll", "went", "were", "we're", "weren't", "we've", "what", "whatever", "what'll", "what's", "what've", "when", "whence", "whenever", "where", "whereafter", "whereas", "whereby", "wherein", "where's", "whereupon", "wherever", "whether", "which", "whichever", "while", "whilst", "whither", "who", "who'd", "whoever", "whole", "who'll", "whom", "whomever", "who's", "whose", "why", "will", "willing", "wish", "with", "within", "without", "wonder", "won't", "would", "wouldn't", "x", "y", "yes", "yet", "you", "you'd", "you'll", "your", "you're", "yours", "yourself", "yourselves", "you've", "z", "zero");
   }

When adding the additional code below to your functions.php file it will remove/hide the slug option for the screen options dropdown as well as the metabox.

// HIDE THE SLUG METABOX AND SLUG SCREEN OPTIONS
   function hide_slug_options() {
 global $post;
 global $pagenow;
 $hide_slugs = "<style type=\"text/css\">#slugdiv, #edit-slug-box, [for=\"slugdiv-hide\"] { display: none; }</style>\n";
 if (is_admin() && $pagenow=='post-new.php' OR $pagenow=='post.php') print($hide_slugs);
   }
   add_action( 'admin_head', 'hide_slug_options'  );
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Remove Author Metabox/Options & Move to Publish MetaBox

Tested on: Wordpress 3.0.1

One of the things that drive me crazy is a cluttered Wordpress Admin area. One of the elements which I now always setup from the start in my functions.php file is removing the Author MetaBox and Screen Options and then adding the option into the publish metabox. In my opinion this just makes sense and keep things clean. This also respects applicable permissions.

To achieve this goal, just copy and past the following code into your functions.php file.

If you feel there is a better way of doing this please suggest.

NOTE: UPDATED THE CODE TO FIX A CODING ISSUE

// MOVE THE AUTHOR METABOX INTO THE PUBLISH METABOX
add_action( 'admin_menu', 'remove_author_metabox' );
add_action( 'post_submitbox_misc_actions', 'move_author_to_publish_metabox' );
function remove_author_metabox() {
    remove_meta_box( 'authordiv', 'post', 'normal' );
}
function move_author_to_publish_metabox() {
    global $post_ID;
    $post = get_post( $post_ID );
    echo '<div id="author" class="misc-pub-section" style="border-top-style:solid; border-top-width:1px; border-top-color:#EEEEEE; border-bottom-width:0px;">Author: ';
    post_author_meta_box( $post );
    echo '</div>';
}
share|improve this answer
1  
@NetConstructor: I just gave it a test yesterday (3.0.4) and yes, the author box is gone, but not moved to the publish box. When looking at the code i can't see any way, because the function is no where triggered... you just added the remove_author_box() fn to admin_menu action hook, but not the move_author_to_publish_box() fn. –  kaiser Feb 1 '11 at 18:55
1  
@kaiser -- your right, after reviewing this I did noticed the issue. I updated the code in my answer so just delete everything you included from this before hand and just past in the full code above. Let me know if this fixes things. Vote up the question and answer if it fixes the problem - CH :) –  NetConstructor.com Feb 1 '11 at 22:29
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Loading scripts conditionally

Here is a way to load scripts only if a particular shortcode or widget is present. source: Loading scripts only if a particular shortcode or widget is present

function has_my_shortcode($posts) {
    if ( empty($posts) )
        return $posts;
    $found = false;
    foreach ($posts as $post) {
        if ( stripos($post->post_content, '[my_shortcode') )
            $found = true;
            break;
        }
    if ($found){
        $urljs = get_bloginfo( 'template_directory' ).IMP_JS;
    wp_register_script('my_script', $urljs.'myscript.js' );
    wp_print_scripts('my_script');
}
    return $posts;
}
add_action('the_posts', 'has_my_shortcode');

And here is how to load scripts only if a certain widget is present

To load the script in the page where the widget is loaded only, you will have to add the is_active_widget() code, in you widget class. E.g., see the default recent comments widget (wp-includes/default-widgets.php, line 602):

class WP_Widget_Recent_Comments extends WP_Widget {
    function WP_Widget_Recent_Comments() {
        $widget_ops = array('classname' => 'widget_recent_comments', 'description' => __( 'The most recent comments' ) );
        $this->WP_Widget('recent-comments', __('Recent Comments'), $widget_ops);
        $this->alt_option_name = 'widget_recent_comments';
        if ( is_active_widget(false, false, $this->id_base) )
        add_action( 'wp_head', array(&$this, 'recent_comments_style') );
        add_action( 'comment_post', array(&$this, 'flush_widget_cache') );
        add_action( 'transition_comment_status', array(&$this, 'flush_widget_cache') );
    }
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Customize the Dashboard

add_action('wp_dashboard_setup', 'my_custom_dashboard_widgets');

function my_custom_dashboard_widgets() {
   global $wp_meta_boxes;

Remove these dashboard widgets...

   unset($wp_meta_boxes['dashboard']['normal']['core']['dashboard_plugins']);
   unset($wp_meta_boxes['dashboard']['side']['core']['dashboard_primary']);
   unset($wp_meta_boxes['dashboard']['side']['core']['dashboard_secondary']);

Add a custom widget called 'Help and Support'

   wp_add_dashboard_widget('custom_help_widget', 'Help and Support', 'custom_dashboard_help');
}

This is the content for your custom widget

 function custom_dashboard_help() {
    echo '<p>Lorum ipsum delor sit amet et nunc</p>';
}
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Exclude default category from public pages

Excludes the default category from the front-facing side of the website.
Code excludes the admin area, else you'll have no way to manage posts assigned with the default category.

add_filter( 'list_terms_exclusions', 'exclude_default_cat' );

function exclude_default_cat( $exclusions ) {
    if( !is_admin() )
        $exclusions .=  "AND t.term_id != " . get_option( 'default_category' ) . " ";
    return $exclusions;
}
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