WP Interactivity API

When to use

Use this skill when the user mentions:

• Interactivity API,

  @wordpress/interactivity

  ,

• data-wp-interactive

  ,

  data-wp-on--*

  ,

  data-wp-bind--*

  ,

  data-wp-context

  ,
• block

  viewScriptModule

  / module-based view scripts,
• hydration issues or “directives don’t fire”.

Inputs required

• Repo root + triage output (

  wp-project-triage

  ).
• Which block/theme/plugin surfaces are affected (frontend, editor, both).
• Any constraints: WP version, whether modules are supported in the build.

Procedure

1) Detect existing usage + integration style

Search for:

• data-wp-interactive

• @wordpress/interactivity

• viewScriptModule

Decide:

• Is this a block providing interactivity via

  block.json

  view script module?
• Is this theme-level interactivity?
• Is this plugin-side “enhance existing markup” usage?

If you’re creating a new interactive block (not just debugging), prefer the official scaffold template:

• @wordpress/create-block-interactive-template

  (via

  @wordpress/create-block

  )

2) Identify the store(s)

Locate store definitions and confirm:

• state shape,
• actions (mutations),
• callbacks/event handlers used by

  data-wp-on--*

  .

3) Server-side rendering (best practice)

Pre-render HTML on the server before outputting to ensure:

• Correct initial state in the HTML before JavaScript loads (no layout shift).
• SEO benefits and faster perceived load time.
• Seamless hydration when the client-side JavaScript takes over.

Enable server directive processing

For components using

block.json

, add

supports.interactivity

:

{
  "supports": {
    "interactivity": true
  }
}

For themes/plugins without

block.json

, use

wp_interactivity_process_directives()

to process directives.

Initialize state/context in PHP

Use

wp_interactivity_state()

to define initial global state:

wp_interactivity_state( 'myPlugin', array(
  'items'    => array( 'Apple', 'Banana', 'Cherry' ),
  'hasItems' => true,
));

For local context, use

wp_interactivity_data_wp_context()

:

<?php
$context = array( 'isOpen' => false );
?>
<div <?php echo wp_interactivity_data_wp_context( $context ); ?>>
  ...
</div>

Define derived state in PHP

When derived state affects initial HTML rendering, replicate the logic in PHP:

wp_interactivity_state( 'myPlugin', array(
  'items'    => array( 'Apple', 'Banana' ),
  'hasItems' => function() {
    $state = wp_interactivity_state();
    return count( $state['items'] ) > 0;
  }
));

This ensures directives like

data-wp-bind--hidden="!state.hasItems"

render correctly on first load.

For detailed examples and patterns, see

references/server-side-rendering.md

.

4) Implement or change directives safely

When touching markup directives:

• keep directive usage minimal and scoped,
• prefer stable data attributes that map clearly to store state,
• ensure server-rendered markup + client hydration align.

WordPress 6.9 changes:

• data-wp-ignore

  is deprecated and will be removed in future versions. It broke context inheritance and caused issues with client-side navigation. Avoid using it.
• Unique directive IDs: Multiple directives of the same type can now exist on one element using the

  ---

  separator (e.g.,

  data-wp-on--click---plugin-a="..."

  and

  data-wp-on--click---plugin-b="..."

  ).
• New TypeScript types:

  AsyncAction<ReturnType>

  and

  TypeYield<T>

  help with async action typing.

For quick directive reminders, see

references/directives-quickref.md

.

5) Build/tooling alignment

Verify the repo supports the required module build path:

• if it uses

  @wordpress/scripts

  , prefer its conventions.
• if it uses custom bundling, confirm module output is supported.

6) Debug common failure modes

If “nothing happens” on interaction:

• confirm the

  viewScriptModule

  is enqueued/loaded,
• confirm the DOM element has

  data-wp-interactive

  ,
• confirm the store namespace matches the directive’s value,
• confirm there are no JS errors before hydration.

See

references/debugging.md

.

Verification

• wp-project-triage

  indicates

  signals.usesInteractivityApi: true

  after your change (if applicable).
• Manual smoke test: directive triggers and state updates as expected.
• If tests exist: add/extend Playwright E2E around the interaction path.

Failure modes / debugging

• Directives present but inert:
  • view script not loading, wrong module entrypoint, or missing

    data-wp-interactive

    .
• Hydration mismatch / flicker:
  • server markup differs from client expectations; simplify or align initial state.
  • derived state not defined in PHP: use

    wp_interactivity_state()

    with closures.
• Initial content missing or wrong:

  • supports.interactivity

    not set in

    block.json

    (for blocks).

  • wp_interactivity_process_directives()

    not called (for themes/plugins).
  • state/context not initialized in PHP before render.
• Layout shift on load:
  • derived state like

    state.hasItems

    missing on server, causing

    hidden

    attribute to be absent.
• Performance regressions:
  • overly broad interactive roots; scope interactivity to smaller subtrees.
• Client-side navigation issues (WordPress 6.9):

  • getServerState()

    and

    getServerContext()

    now reset between page transitions—ensure your code doesn't assume stale values persist.
  • Router regions now support

    attachTo

    for rendering overlays (modals, pop-ups) dynamically.

Escalation

• If repo build constraints are unclear, ask: "Is this using

  @wordpress/scripts

  or a custom bundler (webpack/vite)?"
• Consult:

  • references/server-side-rendering.md

  • references/directives-quickref.md

  • references/debugging.md