What is Theme.json and How Does it Work?
As the WordPress Gutenberg block editor continues to evolve, theme developers face challenges when integrating it into their work. Customizing block styles and managing default color palettes has been a headache, requiring editing multiple files and recreating settings when switching themes. WordPress 5.8 introduced a new feature called theme.json, which allows for finer control and configuration of the block editor. This feature has further developed with the release of WordPress 5.9, where theme.json v2 was introduced. In this article, we will explore what is theme.json and how it works.
What is theme.json?
The purpose of theme.json is to provide a centralized file within the theme directory that defines various settings for the block editor. Instead of relying on multiple theme support flags or alternative methods, theme.json offers a canonical way to define these settings. This centralization simplifies the customization process and promotes consistency across themes.
Granular Control at the Block Level
One of the important benefits of theme.json is its capability to control settings at the block level, allowing for more granularity. This means that specific settings can be applied to individual blocks, while the rest of the blocks can use a common preset. For example, a particular preset can be used for a table block, while the remaining blocks use the default preset.
Efficient Style Management
Another important aspect of theme.json is its role in managing styles. By structuring style properties in the theme.json file, the Block Editor can effectively manage CSS from different sources, such as the user, theme, and core CSS. This helps reduce the amount of CSS that needs to be loaded and prevents conflicts between different styles.
CSS Custom Properties for Consistency
To facilitate shared values across a site, theme.json introduces the use of CSS Custom Properties, also known as CSS Variables. Presets such as color palettes, font sizes, and gradients declared in the theme are converted to CSS Custom Properties and enqueued for both the front-end and the editor. Additionally, theme developers can create their own CSS Custom Properties using the custom field in theme.json.
Understanding the Structure of theme.json
The structure of the theme.json file consists of different sections, including settings, styles, customTemplates, and templateParts. The version field specifies the format of the file, with the current version being v2. The settings section defines various configuration options for the block editor, and these settings can be extended and modified by themes using the add_theme_support function. Backward compatibility is maintained with existing add_theme_support declarations, which are retrofitted into the appropriate categories in theme.json.
Harnessing the Power of Presets
Presets are an integral part of the settings section and allow for the definition of values that are shown to the user through UI controls. Presets can be defined for color palettes, gradients, typography (font sizes and font families), and spacing. By defining presets in theme.json, themes can benefit from automatic translation, CSS class generation, and enqueuing of corresponding CSS.
Unlocking Customization with CSS Custom Properties
In addition to presets, theme developers can create their own CSS Custom Properties using the custom field in theme.json. These custom properties follow a naming schema of “–wp–custom–<variable-name>” and provide themes with the flexibility to define their own style-related properties.
Overall, theme.json provides a powerful mechanism to configure the block editor in WordPress, offering fine-grained control over settings, style management, and the use of CSS Custom Properties. With its ability to define presets and custom properties, theme developers can create more consistent and customizable experiences for users.
Sarah Adams is a seasoned web developer, digital marketer, and the esteemed editor of MasterFSE.com, a premier online resource for WordPress site setup and design. With over a decade of experience in the field, Sarah has become a prominent figure in the web development community, renowned for her expertise and passion for creating visually stunning and user-friendly websites.
Sarah's journey into the world of web development began during her college years, where she discovered her knack for coding and design. She immersed herself in learning various programming languages, mastering the art of creating dynamic and interactive websites. Her insatiable curiosity and drive led her to explore WordPress, a platform that quickly became her true calling.
As the editor of MasterFSE.com, Sarah combines her technical prowess with her exceptional communication skills to provide step-by-step guides, insightful tutorials, and in-depth articles, empowering aspiring web developers and designers to unlock the full potential of WordPress. Her dedication to simplifying complex concepts and sharing her wealth of knowledge has earned her a loyal following of enthusiasts and professionals alike.
Beyond her role at MasterFSE.com, Sarah actively contributes to the WordPress community through speaking engagements, workshops, and mentoring programs. She firmly believes in the transformative power of the web and strives to inspire others to create remarkable online experiences.