"Block" is the abstract term used to describe units of markup that, composed together, form the content or layout of a webpage. The idea combines concepts of what in WordPress today we achieve with shortcodes, custom HTML, and embed discovery into a single consistent API and user experience.
For more context, refer to What Are Little Blocks Made Of? from the Make WordPress Design blog.
The following documentation outlines steps you as a developer will need to follow to add your own custom blocks to WordPress's editor interfaces.
Install the module
npm install @wordpress/blocks --saveThis package assumes that your code will run in an ES2015+ environment. If you're using an environment that has limited or no support for ES2015+ such as lower versions of IE then using core-js or @babel/polyfill will add support for these methods. Learn more about it in Babel docs.
If you're not already accustomed to working with JavaScript in your WordPress plugins, you may first want to reference the guide on Including CSS & JavaScript in the Theme Handbook.
At a minimum, you will need to enqueue scripts for your block as part of a enqueue_block_editor_assets action callback, with a dependency on the wp-blocks and wp-element script handles:
<?php
// myplugin.php
function myplugin_enqueue_block_editor_assets() {
wp_enqueue_script(
'myplugin-block',
plugins_url( 'block.js', __FILE__ ),
array( 'wp-blocks', 'wp-element' )
);
}
add_action( 'enqueue_block_editor_assets', 'myplugin_enqueue_block_editor_assets' );The enqueue_block_editor_assets hook is only run in the Gutenberg editor context when the editor is ready to receive additional scripts and stylesheets. There is also an enqueue_block_assets hook which is run under both the editor and front-end contexts. This should be used to enqueue stylesheets common to the front-end and the editor. (The rules can be overridden in the editor-specific stylesheet if necessary.)
The following sections will describe what you'll need to include in block.js to describe the behavior of your custom block.
Note that all JavaScript code samples in this document are enclosed in a function that is evaluated immediately afterwards. We recommend using either ES6 modules as used in this project (documentation on setting up a plugin with Webpack + ES6 modules coming soon) or these "immediately-invoked function expressions" as used in this document. Both of these methods ensure that your plugin's variables will not pollute the global window object, which could cause incompatibilities with WordPress core or with other plugins.
Let's imagine you wanted to define a block to show a randomly generated image in a post's content using lorempixel.com. The service provides a choice of category and you'd like to offer this as an option when editing the post.
Take a step back and consider the ideal workflow for adding a new random image:
- Insert the block. It should be shown in some empty state, with an option to choose a category in a select dropdown.
- Upon confirming my selection, a preview of the image should be shown next to the dropdown.
At this point, you might realize that while you'd want some controls to be shown when editing content, the markup included in the published post might not appear the same (your visitors should not see a dropdown field when reading your content).
This leads to the first requirement of describing a block:
You will need to provide implementations both for what's to be shown in an editor and what's to be saved with the published content.
To eliminate redundant effort here, share common behaviors by splitting your code up into components.
Now that we've considered user interaction, you should think about the underlying values that determine the markup generated by your block. In our example, the output is affected only when the category changes. Put another way: the output of a block is a function of its attributes.
The category, a simple string, is the only thing we require to be able to generate the image we want to include in the published content. We call these underlying values of a block instance its attributes.
With these concepts in mind, let's explore an implementation of our random image block:
<?php
// random-image.php
function random_image_enqueue_block_editor_assets() {
wp_enqueue_script(
'random-image-block',
plugins_url( 'block.js', __FILE__ ),
array( 'wp-blocks', 'wp-element' )
);
}
add_action( 'enqueue_block_editor_assets', 'random_image_enqueue_block_editor_assets' );// block.js
( function( blocks, element ) {
var el = element.createElement,
source = blocks.source;
function RandomImage( props ) {
var src = 'http://lorempixel.com/400/200/' + props.category;
return el( 'img', {
src: src,
alt: props.category
} );
}
blocks.registerBlockType( 'myplugin/random-image', {
title: 'Random Image',
icon: 'format-image',
category: 'text',
attributes: {
category: {
type: 'string',
source: 'attribute',
attribute: 'alt',
selector: 'img',
}
},
edit: function( props ) {
var category = props.attributes.category,
children;
function setCategory( event ) {
var selected = event.target.querySelector( 'option:checked' );
props.setAttributes( { category: selected.value } );
event.preventDefault();
}
children = [];
if ( category ) {
children.push( RandomImage( { category: category } ) );
}
children.push(
el( 'select', { value: category, onChange: setCategory },
el( 'option', null, '- Select -' ),
el( 'option', { value: 'sports' }, 'Sports' ),
el( 'option', { value: 'animals' }, 'Animals' ),
el( 'option', { value: 'nature' }, 'Nature' )
)
);
return el( 'form', { onSubmit: setCategory }, children );
},
save: function( props ) {
return RandomImage( { category: props.attributes.category } );
}
} );
} )(
window.wp.blocks,
window.wp.element
);Let's briefly review a few items you might observe in the implementation:
- When registering a new block, you must prefix its name with a namespace for your plugin. This helps prevent conflicts when more than one plugin registers a block with the same name.
- You will use
createElementto describe the structure of your block's markup. See the Element documentation for more information. - Extracting
RandomImageto a separate function allows us to reuse it in both the editor-specific interface and the published content. - The
editfunction should handle any case where an attribute is unset, as in the case of the block being newly inserted. - We only change the attributes of a block by calling the
setAttributeshelper. Never assign a value on the attributes object directly. - React provides conveniences for working with
selectelement withvalueandonChangeprops.
By concerning yourself only with describing the markup of a block given its attributes, you need not worry about maintaining the state of the page, or how your block interacts in the context of the surrounding editor.
But how does the markup become an object of attributes? We need a pattern for encoding the values into the published post's markup, and then retrieving them the next time the post is edited. This is the motivation for the block's attributes property. The shape of this object matches that of the attributes object we'd like to receive, where each value is a source which tries to find the desired value from the markup of the block.
In the random image block above, we've given the alt attribute of the image a secondary responsibility of tracking the selected category. There are a few other ways we could have achieved this, but the category value happens to work well as an alt descriptor. In the attributes property, we define an object with a key of category whose value tries to find this alt attribute of the markup. If it's successful, the category's value in our edit and save functions will be assigned. In the case of a new block or invalid markup, this value would be undefined, so we adjust our return value accordingly.
# cloneBlock
Given a block object, returns a copy of the block object, optionally merging new attributes and/or replacing its inner blocks.
Parameters
- block
Object: Block instance. - mergeAttributes
Object: Block attributes. - newInnerBlocks
?Array: Nested blocks.
Returns
Object: A cloned block.
# createBlock
Returns a block object given its type and attributes.
Parameters
- name
string: Block name. - attributes
Object: Block attributes. - innerBlocks
?Array: Nested blocks.
Returns
Object: Block object.
# createBlocksFromInnerBlocksTemplate
Given an array of InnerBlocks templates or Block Objects, returns an array of created Blocks from them. It handles the case of having InnerBlocks as Blocks by converting them to the proper format to continue recursively.
Parameters
- innerBlocksOrTemplate
Array: Nested blocks or InnerBlocks templates.
Returns
Array<Object>: Array of Block objects.
# doBlocksMatchTemplate
Checks whether a list of blocks matches a template by comparing the block names.
Parameters
- blocks
Array: Block list. - template
Array: Block template.
Returns
boolean: Whether the list of blocks matches a templates
# findTransform
Given an array of transforms, returns the highest-priority transform where the predicate function returns a truthy value. A higher-priority transform is one with a lower priority value (i.e. first in priority order). Returns null if the transforms set is empty or the predicate function returns a falsey value for all entries.
Parameters
- transforms
Array<Object>: Transforms to search. - predicate
Function: Function returning true on matching transform.
Returns
?Object: Highest-priority transform candidate.
# getBlockAttributes
Returns the block attributes of a registered block node given its type.
Parameters
- blockTypeOrName
(string|Object): Block type or name. - innerHTML
string: Raw block content. - attributes
?Object: Known block attributes (from delimiters).
Returns
Object: All block attributes.
# getBlockContent
Given a block object, returns the Block's Inner HTML markup.
Parameters
- block
Object: Block instance.
Returns
string: HTML.
# getBlockDefaultClassName
Returns the block's default classname from its name.
Parameters
- blockName
string: The block name.
Returns
string: The block's default class.
# getBlockFromExample
Create a block object from the example API.
Parameters
- name
string: - example
Object:
Returns
Object: block.
# getBlockMenuDefaultClassName
Returns the block's default menu item classname from its name.
Parameters
- blockName
string: The block name.
Returns
string: The block's default menu item class.
# getBlockSupport
Returns the block support value for a feature, if defined.
Parameters
- nameOrType
(string|Object): Block name or type object - feature
string: Feature to retrieve - defaultSupports
*: Default value to return if not explicitly defined
Returns
?*: Block support value
# getBlockTransforms
Returns normal block transforms for a given transform direction, optionally
for a specific block by name, or an empty array if there are no transforms.
If no block name is provided, returns transforms for all blocks. A normal
transform object includes blockName as a property.
Parameters
- direction
string: Transform direction ("to", "from"). - blockTypeOrName
(string|Object): Block type or name.
Returns
Array: Block transforms for direction.
# getBlockType
Returns a registered block type.
Parameters
- name
string: Block name.
Returns
?Object: Block type.
# getBlockTypes
Returns all registered blocks.
Returns
Array: Block settings.
# getBlockVariations
Returns an array with the variations of a given block type.
Parameters
- blockName
string: Name of block (example: “core/columns”). - scope
[WPBlockVariationScope]: Block variation scope name.
Returns
(Array<WPBlockVariation>|void): Block variations.
# getCategories
Returns all the block categories.
Returns
Array<WPBlockCategory>: Block categories.
# getChildBlockNames
Returns an array with the child blocks of a given block.
Parameters
- blockName
string: Name of block (example: “latest-posts”).
Returns
Array: Array of child block names.
# getDefaultBlockName
Retrieves the default block name.
Returns
?string: Block name.
# getFreeformContentHandlerName
Retrieves name of block handling non-block content, or undefined if no handler has been defined.
Returns
?string: Block name.
# getGroupingBlockName
Retrieves name of block used for handling grouping interactions.
Returns
?string: Block name.
# getPhrasingContentSchema
Undocumented declaration.
# getPossibleBlockTransformations
Returns an array of block types that the set of blocks received as argument can be transformed into.
Parameters
- blocks
Array: Blocks array.
Returns
Array: Block types that the blocks argument can be transformed to.
# getSaveContent
Given a block type containing a save render implementation and attributes, returns the static markup to be saved.
Parameters
- blockTypeOrName
(string|Object): Block type or name. - attributes
Object: Block attributes. - innerBlocks
?Array: Nested blocks.
Returns
string: Save content.
# getSaveElement
Given a block type containing a save render implementation and attributes, returns the enhanced element to be saved or string when raw HTML expected.
Parameters
- blockTypeOrName
(string|Object): Block type or name. - attributes
Object: Block attributes. - innerBlocks
?Array: Nested blocks.
Returns
(Object|string): Save element or raw HTML string.
# getUnregisteredTypeHandlerName
Retrieves name of block handling unregistered block types, or undefined if no handler has been defined.
Returns
?string: Block name.
# hasBlockSupport
Returns true if the block defines support for a feature, or false otherwise.
Parameters
- nameOrType
(string|Object): Block name or type object. - feature
string: Feature to test. - defaultSupports
boolean: Whether feature is supported by default if not explicitly defined.
Returns
boolean: Whether block supports feature.
# hasChildBlocks
Returns a boolean indicating if a block has child blocks or not.
Parameters
- blockName
string: Name of block (example: “latest-posts”).
Returns
boolean: True if a block contains child blocks and false otherwise.
# hasChildBlocksWithInserterSupport
Returns a boolean indicating if a block has at least one child block with inserter support.
Parameters
- blockName
string: Block type name.
Returns
boolean: True if a block contains at least one child blocks with inserter support and false otherwise.
# isReusableBlock
Determines whether or not the given block is a reusable block. This is a special block type that is used to point to a global block stored via the API.
Parameters
- blockOrType
Object: Block or Block Type to test.
Returns
boolean: Whether the given block is a reusable block.
# isUnmodifiedDefaultBlock
Determines whether the block is a default block and its attributes are equal to the default attributes which means the block is unmodified.
Parameters
- block
WPBlock: Block Object
Returns
boolean: Whether the block is an unmodified default block
# isValidBlockContent
Returns true if the parsed block is valid given the input content. A block is considered valid if, when serialized with assumed attributes, the content matches the original value.
Logs to console in development environments when invalid.
Parameters
- blockTypeOrName
(string|Object): Block type. - attributes
Object: Parsed block attributes. - originalBlockContent
string: Original block content.
Returns
boolean: Whether block is valid.
# isValidIcon
Function that checks if the parameter is a valid icon.
Parameters
- icon
*: Parameter to be checked.
Returns
boolean: True if the parameter is a valid icon and false otherwise.
# normalizeIconObject
Function that receives an icon as set by the blocks during the registration and returns a new icon object that is normalized so we can rely on just on possible icon structure in the codebase.
Parameters
- icon
WPBlockTypeIconRender: Render behavior of a block type icon; one of a Dashicon slug, an element, or a component.
Returns
WPBlockTypeIconDescriptor: Object describing the icon.
# parse
Parses the post content with a PegJS grammar and returns a list of blocks.
Parameters
- content
string: The post content.
Returns
Array: Block list.
# parseWithAttributeSchema
Given a block's raw content and an attribute's schema returns the attribute's value depending on its source.
Parameters
- innerHTML
string: Block's raw content. - attributeSchema
Object: Attribute's schema.
Returns
*: Attribute value.
# pasteHandler
Converts an HTML string to known blocks. Strips everything else.
Parameters
- options
Object: - options.HTML
[string]: The HTML to convert. - options.plainText
[string]: Plain text version. - options.mode
[string]: Handle content as blocks or inline content. _ 'AUTO': Decide based on the content passed. _ 'INLINE': Always handle as inline content, and return string. * 'BLOCKS': Always handle as blocks, and return array of blocks. - options.tagName
[Array]: The tag into which content will be inserted.
Returns
(Array|string): A list of blocks or a string, depending onhandlerMode.
# rawHandler
Converts an HTML string to known blocks.
Parameters
- $1
Object: - $1.HTML
string: The HTML to convert.
Returns
Array: A list of blocks.
# registerBlockCollection
Registers a new block collection to group blocks in the same namespace in the inserter.
Parameters
- namespace
string: The namespace to group blocks by in the inserter; corresponds to the block namespace. - settings
Object: The block collection settings. - settings.title
string: The title to display in the block inserter. - settings.icon
[Object]: The icon to display in the block inserter.
# registerBlockStyle
Registers a new block style variation for the given block.
Parameters
- blockName
string: Name of block (example: “core/latest-posts”). - styleVariation
Object: Object containingnamewhich is the class name applied to the block andlabelwhich identifies the variation to the user.
# registerBlockType
Registers a new block provided a unique name and an object defining its behavior. Once registered, the block is made available as an option to any editor interface where blocks are implemented.
Parameters
- name
string: Block name. - settings
Object: Block settings.
Returns
?WPBlock: The block, if it has been successfully registered; otherwiseundefined.
# registerBlockVariation
Registers a new block variation for the given block type.
Parameters
- blockName
string: Name of the block (example: “core/columns”). - variation
WPBlockVariation: Object describing a block variation.
# serialize
Takes a block or set of blocks and returns the serialized post content.
Parameters
- blocks
Array: Block(s) to serialize. - options
WPBlockSerializationOptions: Serialization options.
Returns
string: The post content.
# setCategories
Sets the block categories.
Parameters
- categories
Array<WPBlockCategory>: Block categories.
# setDefaultBlockName
Assigns the default block name.
Parameters
- name
string: Block name.
# setFreeformContentHandlerName
Assigns name of block for handling non-block content.
Parameters
- blockName
string: Block name.
# setGroupingBlockName
Assigns name of block for handling block grouping interactions.
Parameters
- name
string: Block name.
# setUnregisteredTypeHandlerName
Assigns name of block handling unregistered block types.
Parameters
- blockName
string: Block name.
# switchToBlockType
Switch one or more blocks into one or more blocks of the new block type.
Parameters
- blocks
(Array|Object): Blocks array or block object. - name
string: Block name.
Returns
?Array: Array of blocks or null.
# synchronizeBlocksWithTemplate
Synchronize a block list with a block template.
Synchronizing a block list with a block template means that we loop over the blocks keep the block as is if it matches the block at the same position in the template (If it has the same name) and if doesn't match, we create a new block based on the template. Extra blocks not present in the template are removed.
Parameters
- blocks
Array: Block list. - template
Array: Block template.
Returns
Array: Updated Block list.
# unregisterBlockStyle
Unregisters a block style variation for the given block.
Parameters
- blockName
string: Name of block (example: “core/latest-posts”). - styleVariationName
string: Name of class applied to the block.
# unregisterBlockType
Unregisters a block.
Parameters
- name
string: Block name.
Returns
?WPBlock: The previous block value, if it has been successfully unregistered; otherwiseundefined.
# unregisterBlockVariation
Unregisters a block variation defined for the given block type.
Parameters
- blockName
string: Name of the block (example: “core/columns”). - variationName
string: Name of the variation defined for the block.
# updateCategory
Updates a category.
Parameters
- slug
string: Block category slug. - category
WPBlockCategory: Object containing the category properties that should be updated.
# withBlockContentContext
A Higher Order Component used to inject BlockContent using context to the wrapped component.
Returns
WPComponent: Enhanced component with injected BlockContent as prop.
