Even if you don’t understand everything about the functions.php file, you can learn a lot by going through it and looking at everything and reading the comments. When you get to something you don’t understand, just type a question into Chrome or the WordPress Codex and you’ll get the answer.
See also the link to my blog post notes on Customizing WordPress #6 – Introduction to the functions template – YouTube Video, Sept 28, 2017. The video is a good basic introduction.
See also WordPress All-In-One For Dummies, 2017 3rd edition for more information on functions. php on pages 444, 453, 455, 456, 509-510, 532, 567.
p 444+445: Template (ex: index.php) and function files (ex: functions.php) end with the extension .php. PHP is a scripting language used in WordPress, which your web server recognizes and interprets as such.
Within this set of PHP files is all the information your browser and web server need to make your website [Your theme folder also needs a style.css file to make your website].
Templates are individual files. Each template file provides the structure in which your content will display. A theme is a folder (a directory) which contain a set of templates. The theme uses templates to make the whole site.
Knowing where the WordPress theme files are located on your web server means that you can edit them as desired.
I’ll be updating this post with links to the relevant parts of the WordPress Codex.
So here’s the 2014 theme’s complete functions.php [Youwant to copy and download this file from your site with filezilla. And then you can open it in notepad ++ to work on it]:
<?php
/**
* Twenty Fourteen functions and definitions
*
* Set up the theme and provides some helper functions, which are used in the
* theme as custom template tags. Others are attached to action and filter
* hooks in WordPress to change core functionality.
*
* When using a child theme you can override certain functions (those wrapped
* in a function_exists() call) by defining them first in your child theme’s
* functions.php file. The child theme’s functions.php file is included before
* the parent theme’s file, so the child theme functions would be used.
*
* @link https://codex.wordpress.org/Theme_Development
* @link https://codex.wordpress.org/Child_Themes
*
* Functions that are not pluggable (not wrapped in function_exists()) are
* instead attached to a filter or action hook.
*
* For more information on hooks, actions, and filters,
* @link https://codex.wordpress.org/Plugin_API
*
* @package WordPress
* @subpackage Twenty_Fourteen
* @since Twenty Fourteen 1.0
*/
/**
* Set up the content width value based on the theme’s design.
*
* @see twentyfourteen_content_width()
*
* @since Twenty Fourteen 1.0
*/
if ( ! isset( $content_width ) ) {
$content_width = 474;
}
/**
* Twenty Fourteen only works in WordPress 3.6 or later.
*/
if ( version_compare( $GLOBALS[‘wp_version’], ‘3.6’, ‘<‘ ) ) {
require get_template_directory() . ‘/inc/back-compat.php’;
}
if ( ! function_exists( ‘twentyfourteen_setup’ ) ) :
/**
* Twenty Fourteen setup.
*
* Set up theme defaults and registers support for various WordPress features.
*
* Note that this function is hooked into the after_setup_theme hook, which
* runs before the init hook. The init hook is too late for some features, such
* as indicating support post thumbnails.
*
* @since Twenty Fourteen 1.0
*/
function twentyfourteen_setup() {
/*
* Make Twenty Fourteen available for translation.
*
* Translations can be filed at WordPress.org. See: https://translate.wordpress.org/projects/wp-themes/twentyfourteen
* If you’re building a theme based on Twenty Fourteen, use a find and
* replace to change ‘twentyfourteen’ to the name of your theme in all
* template files.
*/
load_theme_textdomain( ‘twentyfourteen’ );
// This theme styles the visual editor to resemble the theme style.
add_editor_style( array( ‘css/editor-style.css’, twentyfourteen_font_url(), ‘genericons/genericons.css’ ) );
// Add RSS feed links to <head> for posts and comments.
add_theme_support( ‘automatic-feed-links’ );
// Enable support for Post Thumbnails, and declare two sizes.
add_theme_support( ‘post-thumbnails’ );
set_post_thumbnail_size( 672, 372, true );
add_image_size( ‘twentyfourteen-full-width’, 1038, 576, true );
// This theme uses wp_nav_menu() in two locations.
register_nav_menus( array(
‘primary’ => __( ‘Top primary menu’, ‘twentyfourteen’ ),
‘secondary’ => __( ‘Secondary menu in left sidebar’, ‘twentyfourteen’ ),
) );
/*
* Switch default core markup for search form, comment form, and comments
* to output valid HTML5.
*/
add_theme_support( ‘html5’, array(
‘search-form’, ‘comment-form’, ‘comment-list’, ‘gallery’, ‘caption’
) );
/*
* Enable support for Post Formats.
* See https://codex.wordpress.org/Post_Formats
*/
add_theme_support( ‘post-formats’, array(
‘aside’, ‘image’, ‘video’, ‘audio’, ‘quote’, ‘link’, ‘gallery’,
) );
// This theme allows users to set a custom background.
add_theme_support( ‘custom-background’, apply_filters( ‘twentyfourteen_custom_background_args’, array(
‘default-color’ => ‘f5f5f5’,
) ) );
// Add support for featured content.
add_theme_support( ‘featured-content’, array(
‘featured_content_filter’ => ‘twentyfourteen_get_featured_posts’,
‘max_posts’ => 6,
) );
// This theme uses its own gallery styles.
add_filter( ‘use_default_gallery_style’, ‘__return_false’ );
// Indicate widget sidebars can use selective refresh in the Customizer.
add_theme_support( ‘customize-selective-refresh-widgets’ );
}
endif; // twentyfourteen_setup
add_action( ‘after_setup_theme’, ‘twentyfourteen_setup’ );
/**
* Adjust content_width value for image attachment template.
*
* @since Twenty Fourteen 1.0
*/
function twentyfourteen_content_width() {
if ( is_attachment() && wp_attachment_is_image() ) {
$GLOBALS[‘content_width’] = 810;
}
}
add_action( ‘template_redirect’, ‘twentyfourteen_content_width’ );
/**
* Getter function for Featured Content Plugin.
*
* @since Twenty Fourteen 1.0
*
* @return array An array of WP_Post objects.
*/
function twentyfourteen_get_featured_posts() {
/**
* Filter the featured posts to return in Twenty Fourteen.
*
* @since Twenty Fourteen 1.0
*
* @param array|bool $posts Array of featured posts, otherwise false.
*/
return apply_filters( ‘twentyfourteen_get_featured_posts’, array() );
}
/**
* A helper conditional function that returns a boolean value.
*
* @since Twenty Fourteen 1.0
*
* @return bool Whether there are featured posts.
*/
function twentyfourteen_has_featured_posts() {
return ! is_paged() && (bool) twentyfourteen_get_featured_posts();
}
/**
* Register three Twenty Fourteen widget areas.
*
* @since Twenty Fourteen 1.0
*/
function twentyfourteen_widgets_init() {
require get_template_directory() . ‘/inc/widgets.php’;
register_widget( ‘Twenty_Fourteen_Ephemera_Widget’ );
register_sidebar( array(
‘name’ => __( ‘Primary Sidebar’, ‘twentyfourteen’ ),
‘id’ => ‘sidebar-1’,
‘description’ => __( ‘Main sidebar that appears on the left.’, ‘twentyfourteen’ ),
‘before_widget’ => ‘<aside id=”%1$s” class=”widget %2$s”>’,
‘after_widget’ => ‘</aside>’,
‘before_title’ => ‘<h1 class=”widget-title”>’,
‘after_title’ => ‘</h1>’,
) );
register_sidebar( array(
‘name’ => __( ‘Content Sidebar’, ‘twentyfourteen’ ),
‘id’ => ‘sidebar-2’,
‘description’ => __( ‘Additional sidebar that appears on the right.’, ‘twentyfourteen’ ),
‘before_widget’ => ‘<aside id=”%1$s” class=”widget %2$s”>’,
‘after_widget’ => ‘</aside>’,
‘before_title’ => ‘<h1 class=”widget-title”>’,
‘after_title’ => ‘</h1>’,
) );
register_sidebar( array(
‘name’ => __( ‘Footer Widget Area’, ‘twentyfourteen’ ),
‘id’ => ‘sidebar-3’,
‘description’ => __( ‘Appears in the footer section of the site.’, ‘twentyfourteen’ ),
‘before_widget’ => ‘<aside id=”%1$s” class=”widget %2$s”>’,
‘after_widget’ => ‘</aside>’,
‘before_title’ => ‘<h1 class=”widget-title”>’,
‘after_title’ => ‘</h1>’,
) );
}
add_action( ‘widgets_init’, ‘twentyfourteen_widgets_init’ );
/**
* Register Lato Google font for Twenty Fourteen.
*
* @since Twenty Fourteen 1.0
*
* @return string
*/
function twentyfourteen_font_url() {
$font_url = ”;
/*
* Translators: If there are characters in your language that are not supported
* by Lato, translate this to ‘off’. Do not translate into your own language.
*/
if ( ‘off’ !== _x( ‘on’, ‘Lato font: on or off’, ‘twentyfourteen’ ) ) {
$query_args = array(
‘family’ => urlencode( ‘Lato:300,400,700,900,300italic,400italic,700italic’ ),
‘subset’ => urlencode( ‘latin,latin-ext’ ),
);
$font_url = add_query_arg( $query_args, ‘https://fonts.googleapis.com/css’ );
}
return $font_url;
}
/**
* Enqueue scripts and styles for the front end.
*
* @since Twenty Fourteen 1.0
*/
function twentyfourteen_scripts() {
// Add Lato font, used in the main stylesheet.
wp_enqueue_style( ‘twentyfourteen-lato’, twentyfourteen_font_url(), array(), null );
// Add Genericons font, used in the main stylesheet.
wp_enqueue_style( ‘genericons’, get_template_directory_uri() . ‘/genericons/genericons.css’, array(), ‘3.0.3’ );
// Load our main stylesheet.
wp_enqueue_style( ‘twentyfourteen-style’, get_stylesheet_uri() );
// Load the Internet Explorer specific stylesheet.
wp_enqueue_style( ‘twentyfourteen-ie’, get_template_directory_uri() . ‘/css/ie.css’, array( ‘twentyfourteen-style’ ), ‘20131205’ );
wp_style_add_data( ‘twentyfourteen-ie’, ‘conditional’, ‘lt IE 9’ );
if ( is_singular() && comments_open() && get_option( ‘thread_comments’ ) ) {
wp_enqueue_script( ‘comment-reply’ );
}
if ( is_singular() && wp_attachment_is_image() ) {
wp_enqueue_script( ‘twentyfourteen-keyboard-image-navigation’, get_template_directory_uri() . ‘/js/keyboard-image-navigation.js’, array( ‘jquery’ ), ‘20130402’ );
}
if ( is_active_sidebar( ‘sidebar-3’ ) ) {
wp_enqueue_script( ‘jquery-masonry’ );
}
if ( is_front_page() && ‘slider’ == get_theme_mod( ‘featured_content_layout’ ) ) {
wp_enqueue_script( ‘twentyfourteen-slider’, get_template_directory_uri() . ‘/js/slider.js’, array( ‘jquery’ ), ‘20131205’, true );
wp_localize_script( ‘twentyfourteen-slider’, ‘featuredSliderDefaults’, array(
‘prevText’ => __( ‘Previous’, ‘twentyfourteen’ ),
‘nextText’ => __( ‘Next’, ‘twentyfourteen’ )
) );
}
wp_enqueue_script( ‘twentyfourteen-script’, get_template_directory_uri() . ‘/js/functions.js’, array( ‘jquery’ ), ‘20150315’, true );
}
add_action( ‘wp_enqueue_scripts’, ‘twentyfourteen_scripts’ );
/**
* Enqueue Google fonts style to admin screen for custom header display.
*
* @since Twenty Fourteen 1.0
*/
function twentyfourteen_admin_fonts() {
wp_enqueue_style( ‘twentyfourteen-lato’, twentyfourteen_font_url(), array(), null );
}
add_action( ‘admin_print_scripts-appearance_page_custom-header’, ‘twentyfourteen_admin_fonts’ );
/**
* Add preconnect for Google Fonts.
*
* @since Twenty Fourteen 1.9
*
* @param array $urls URLs to print for resource hints.
* @param string $relation_type The relation type the URLs are printed.
* @return array URLs to print for resource hints.
*/
function twentyfourteen_resource_hints( $urls, $relation_type ) {
if ( wp_style_is( ‘twentyfourteen-lato’, ‘queue’ ) && ‘preconnect’ === $relation_type ) {
if ( version_compare( $GLOBALS[‘wp_version’], ‘4.7-alpha’, ‘>=’ ) ) {
$urls[] = array(
‘href’ => ‘https://fonts.gstatic.com’,
‘crossorigin’,
);
} else {
$urls[] = ‘https://fonts.gstatic.com’;
}
}
return $urls;
}
add_filter( ‘wp_resource_hints’, ‘twentyfourteen_resource_hints’, 10, 2 );
if ( ! function_exists( ‘twentyfourteen_the_attached_image’ ) ) :
/**
* Print the attached image with a link to the next attached image.
*
* @since Twenty Fourteen 1.0
*/
function twentyfourteen_the_attached_image() {
$post = get_post();
/**
* Filter the default Twenty Fourteen attachment size.
*
* @since Twenty Fourteen 1.0
*
* @param array $dimensions {
* An array of height and width dimensions.
*
* @type int $height Height of the image in pixels. Default 810.
* @type int $width Width of the image in pixels. Default 810.
* }
*/
$attachment_size = apply_filters( ‘twentyfourteen_attachment_size’, array( 810, 810 ) );
$next_attachment_url = wp_get_attachment_url();
/*
* Grab the IDs of all the image attachments in a gallery so we can get the URL
* of the next adjacent image in a gallery, or the first image (if we’re
* looking at the last image in a gallery), or, in a gallery of one, just the
* link to that image file.
*/
$attachment_ids = get_posts( array(
‘post_parent’ => $post->post_parent,
‘fields’ => ‘ids’,
‘numberposts’ => -1,
‘post_status’ => ‘inherit’,
‘post_type’ => ‘attachment’,
‘post_mime_type’ => ‘image’,
‘order’ => ‘ASC’,
‘orderby’ => ‘menu_order ID’,
) );
// If there is more than 1 attachment in a gallery…
if ( count( $attachment_ids ) > 1 ) {
foreach ( $attachment_ids as $idx => $attachment_id ) {
if ( $attachment_id == $post->ID ) {
$next_id = $attachment_ids[ ( $idx + 1 ) % count( $attachment_ids ) ];
break;
}
}
// get the URL of the next image attachment…
if ( $next_id ) {
$next_attachment_url = get_attachment_link( $next_id );
}
// or get the URL of the first image attachment.
else {
$next_attachment_url = get_attachment_link( reset( $attachment_ids ) );
}
}
printf( ‘<a href=”%1$s” rel=”attachment”>%2$s</a>’,
esc_url( $next_attachment_url ),
wp_get_attachment_image( $post->ID, $attachment_size )
);
}
endif;
if ( ! function_exists( ‘twentyfourteen_list_authors’ ) ) :
/**
* Print a list of all site contributors who published at least one post.
*
* @since Twenty Fourteen 1.0
*/
function twentyfourteen_list_authors() {
$contributor_ids = get_users( array(
‘fields’ => ‘ID’,
‘orderby’ => ‘post_count’,
‘order’ => ‘DESC’,
‘who’ => ‘authors’,
) );
foreach ( $contributor_ids as $contributor_id ) :
$post_count = count_user_posts( $contributor_id );
// Move on if user has not published a post (yet).
if ( ! $post_count ) {
continue;
}
?>
<div class=”contributor”>
<div class=”contributor-info”>
<div class=”contributor-avatar”><?php echo get_avatar( $contributor_id, 132 ); ?></div>
<div class=”contributor-summary”>
<h2 class=”contributor-name”><?php echo get_the_author_meta( ‘display_name’, $contributor_id ); ?></h2>
<p class=”contributor-bio”>
<?php echo get_the_author_meta( ‘description’, $contributor_id ); ?>
</p>
<a class=”button contributor-posts-link” href=”<?php echo esc_url( get_author_posts_url( $contributor_id ) ); ?>”>
<?php printf( _n( ‘%d Article’, ‘%d Articles’, $post_count, ‘twentyfourteen’ ), $post_count ); ?>
</a>
</div><!– .contributor-summary –>
</div><!– .contributor-info –>
</div><!– .contributor –>
<?php
endforeach;
}
endif;
/**
* Extend the default WordPress body classes.
*
* Adds body classes to denote:
* 1. Single or multiple authors.
* 2. Presence of header image except in Multisite signup and activate pages.
* 3. Index views.
* 4. Full-width content layout.
* 5. Presence of footer widgets.
* 6. Single views.
* 7. Featured content layout.
*
* @since Twenty Fourteen 1.0
*
* @param array $classes A list of existing body class values.
* @return array The filtered body class list.
*/
function twentyfourteen_body_classes( $classes ) {
if ( is_multi_author() ) {
$classes[] = ‘group-blog’;
}
if ( get_header_image() ) {
$classes[] = ‘header-image’;
} elseif ( ! in_array( $GLOBALS[‘pagenow’], array( ‘wp-activate.php’, ‘wp-signup.php’ ) ) ) {
$classes[] = ‘masthead-fixed’;
}
if ( is_archive() || is_search() || is_home() ) {
$classes[] = ‘list-view’;
}
if ( ( ! is_active_sidebar( ‘sidebar-2’ ) )
|| is_page_template( ‘page-templates/full-width.php’ )
|| is_page_template( ‘page-templates/contributors.php’ )
|| is_attachment() ) {
$classes[] = ‘full-width’;
}
if ( is_active_sidebar( ‘sidebar-3’ ) ) {
$classes[] = ‘footer-widgets’;
}
if ( is_singular() && ! is_front_page() ) {
$classes[] = ‘singular’;
}
if ( is_front_page() && ‘slider’ == get_theme_mod( ‘featured_content_layout’ ) ) {
$classes[] = ‘slider’;
} elseif ( is_front_page() ) {
$classes[] = ‘grid’;
}
return $classes;
}
add_filter( ‘body_class’, ‘twentyfourteen_body_classes’ );
/**
* Extend the default WordPress post classes.
*
* Adds a post class to denote:
* Non-password protected page with a post thumbnail.
*
* @since Twenty Fourteen 1.0
*
* @param array $classes A list of existing post class values.
* @return array The filtered post class list.
*/
function twentyfourteen_post_classes( $classes ) {
if ( ! post_password_required() && ! is_attachment() && has_post_thumbnail() ) {
$classes[] = ‘has-post-thumbnail’;
}
return $classes;
}
add_filter( ‘post_class’, ‘twentyfourteen_post_classes’ );
/**
* Create a nicely formatted and more specific title element text for output
* in head of document, based on current view.
*
* @since Twenty Fourteen 1.0
*
* @global int $paged WordPress archive pagination page count.
* @global int $page WordPress paginated post page count.
*
* @param string $title Default title text for current view.
* @param string $sep Optional separator.
* @return string The filtered title.
*/
function twentyfourteen_wp_title( $title, $sep ) {
global $paged, $page;
if ( is_feed() ) {
return $title;
}
// Add the site name.
$title .= get_bloginfo( ‘name’, ‘display’ );
// Add the site description for the home/front page.
$site_description = get_bloginfo( ‘description’, ‘display’ );
if ( $site_description && ( is_home() || is_front_page() ) ) {
$title = “$title $sep $site_description”;
}
// Add a page number if necessary.
if ( ( $paged >= 2 || $page >= 2 ) && ! is_404() ) {
$title = “$title $sep ” . sprintf( __( ‘Page %s’, ‘twentyfourteen’ ), max( $paged, $page ) );
}
return $title;
}
add_filter( ‘wp_title’, ‘twentyfourteen_wp_title’, 10, 2 );
// Implement Custom Header features.
require get_template_directory() . ‘/inc/custom-header.php’;
// Custom template tags for this theme.
require get_template_directory() . ‘/inc/template-tags.php’;
// Add Customizer functionality.
require get_template_directory() . ‘/inc/customizer.php’;
/*
* Add Featured Content functionality.
*
* To overwrite in a plugin, define your own Featured_Content class on or
* before the ‘setup_theme’ hook.
*/
if ( ! class_exists( ‘Featured_Content’ ) && ‘plugins.php’ !== $GLOBALS[‘pagenow’] ) {
require get_template_directory() . ‘/inc/featured-content.php’;
}
/**
* Add an `is_customize_preview` function if it is missing.
*
* Enables installing Twenty Fourteen in WordPress versions before 4.0.0 when the
* `is_customize_preview` function was introduced.
*/
if ( ! function_exists( ‘is_customize_preview’ ) ) :
function is_customize_preview() {
global $wp_customize;
return ( $wp_customize instanceof WP_Customize_Manager ) && $wp_customize->is_preview();
}
endif;
