WordPress Release: 4.4.0

TL;DR

WordPress 4.4 "Clifford" introduces significant improvements to the platform's foundation with the REST API infrastructure, responsive images, and embedded content capabilities. This release enhances WordPress's ability to connect with other sites through oEmbed support and improves the mobile experience with responsive images. The REST API infrastructure lays groundwork for developers to build more advanced applications, while Twenty Sixteen becomes the new default theme with a modern, content-focused design.

Highlight of the Release

• Introduction of the WordPress REST API infrastructure
• Responsive images support that automatically serves appropriately sized images to different devices
• Embed support for WordPress posts across different sites
• New Twenty Sixteen default theme with improved typography and mobile experience
• Term metadata API for more flexible taxonomies
• Support for new oEmbed providers including Reddit Comments and Speaker Deck

Migration Guide

REST API Infrastructure

The REST API infrastructure is now included in core, but the endpoints for posts, comments, terms, users, and other WordPress data are still being developed in the REST API plugin. If you're already using the REST API plugin, you should continue to use it until the endpoints are included in core.

Responsive Images

If your theme manipulates images with custom HTML, you may need to update your code to take advantage of the new responsive image features. Review the new template functions like wp_get_attachment_image_srcset() and wp_get_attachment_image_sizes().

Term Metadata

If you've been using a custom solution for term metadata, you should consider migrating to the new core API. The functions mirror those used for post metadata: add_term_meta(), update_term_meta(), delete_term_meta(), and get_term_meta().

Twenty Sixteen

If you're upgrading from an older version and using a default theme, note that Twenty Sixteen will not automatically become your active theme. You can manually activate it from the Appearance > Themes screen.

Upgrade Recommendations

Recommended Upgrade Path

This is a major release with significant new features and improvements. It's recommended that all WordPress sites upgrade to version 4.4.

Before upgrading:

1. Back up your website files and database
2. Test the upgrade on a staging site if possible
3. Update all plugins and themes to their latest versions
4. Check compatibility of critical plugins with WordPress 4.4

Plugin Compatibility

The REST API plugin users should note that WordPress 4.4 will force disable older versions of the plugin (pre-beta5) during upgrade, as they were not configured to gracefully degrade during update.

Theme Compatibility

If you're using a custom theme that manipulates images with custom HTML, you may need to review your code to ensure compatibility with the new responsive images feature.

PHP Compatibility

WordPress 4.4 has been tested with PHP versions 5.2.4 and higher, but we recommend using at least PHP 5.6 for optimal performance and security.

Bug Fixes

Comment Management

• Fixed issues with comment management interface accessibility
• Improved focus handling when replying to comments
• Fixed dynamic title text updates for all languages, not just English

Media Library

• Fixed PHP warning in wp_generate_attachment_metadata() when metadata is not an array
• Fixed support for embedding in non-WordPress sites
• Corrected handling of GIF images in responsive image generation to avoid adding animation to flat images
• Fixed media_sideload_image() to work with PHP streams

User Management

• Fixed password handling in wp_insert_user() to prevent accidental password resets
• Restored pre-4.3 behavior for wp_new_user_notification() to maintain backward compatibility
• Added option to create users without sending notification emails

Editor

• Fixed TinyMCE issues with the link dialog on MacOS
• Improved handling of pasted content from various sources
• Fixed resize handles in newer IE versions when inserting a wpView

Customizer

• Fixed alignment of checkbox control labels
• Corrected issues with sub-nav menu items appearing at root level in preview
• Fixed focus and autofocus on nav_menu_item controls

Taxonomy

• Fixed term metadata deletion when terms are deleted
• Improved handling of non-public taxonomies in query variables

Multisite

• Fixed network admin email setting during network setup
• Improved styling for site status indicators in network admin

Accessibility

• Added missing alt attributes to various images
• Improved form labels and descriptions for the Tags meta box
• Enhanced taxonomies Quick Edit form with better semantics and keyboard navigation

New Features

REST API Infrastructure

The WordPress REST API infrastructure is now included in core, providing a developer-focused interface for accessing WordPress data. This lays the groundwork for building more advanced applications with WordPress as a foundation.

Responsive Images

WordPress now automatically generates and serves appropriately sized images based on the device being used, improving page load times and reducing bandwidth usage. New template functions like wp_get_attachment_image_srcset() and filters allow developers to customize responsive image behavior.

Embedded Content

WordPress 4.4 introduces the ability to embed WordPress posts on other WordPress sites. Simply paste a post URL on its own line and WordPress will automatically embed a preview of that content. This feature works bidirectionally, allowing your content to be embedded on other sites as well.

Twenty Sixteen Theme

The new default theme features a modern design focused on readability with a horizontal scrolling mobile menu, beautiful typography, and a clean layout that works well on any device.

Term Metadata

A new metadata API for taxonomy terms enables developers to store and retrieve custom data associated with categories, tags, and custom taxonomies, similar to post meta.

New oEmbed Providers

WordPress 4.4 adds support for embedding content from Reddit Comments and Speaker Deck.

Security Updates

User Management

• Improved password security by increasing the length of user_pass and user_activation_key fields to 255 characters
• Made the 'illegal_user_logins' check case-insensitive for better security

Embeds

• Added validation for the secret sent via postMessage in wp.receiveEmbedMessage
• Improved security of embedded content

Input Sanitization

• Enhanced sanitization of user inputs in various areas
• Improved escaping of email addresses and IP addresses of comment authors

Performance Improvements

Responsive Images

The new responsive images feature significantly improves page load times by serving appropriately sized images based on the device being used, reducing unnecessary bandwidth usage.

Database Queries

• Eliminated a database query when building the admin menu for non-privileged users
• Added the postmeta_form_keys filter to potentially avoid expensive queries against postmeta

JavaScript Optimizations

• Improved emoji handling for better performance
• Enhanced script loading and execution in the admin interface

HTTP Requests

• Improved handling of HTTP requests with better caching
• Enhanced handling of external resources

Impact Summary

WordPress 4.4 "Clifford" represents a significant step forward in WordPress's evolution as a platform. The introduction of the REST API infrastructure lays the groundwork for more advanced application development, enabling WordPress to serve as a robust foundation for web applications beyond traditional websites.

The responsive images feature addresses a critical need in today's multi-device world, automatically serving appropriately sized images to different devices without requiring additional plugins or custom code. This improves both performance and user experience across all devices.

The embedded content capabilities enhance WordPress's role in the connected web ecosystem, allowing content to flow more seamlessly between WordPress sites. This feature, combined with support for additional oEmbed providers, makes content sharing and reuse more powerful and intuitive.

Term metadata adds important flexibility to WordPress's taxonomy system, enabling developers to build more sophisticated content organization systems without custom database tables or workarounds.

The new Twenty Sixteen theme provides a modern, content-focused design that works well across all devices, showcasing WordPress's capabilities as a publishing platform.

Overall, WordPress 4.4 strengthens the platform's foundation while adding features that improve both the user experience and developer capabilities, positioning WordPress well for future growth and evolution.