Building a New Block — index.asset.php

index.asset.php tells WordPress what scripts to load before index.js. WordPress reads this file during block registration and builds the correct <script> dependency chain. A missing or incorrect dependency causes index.js to silently fail — the block appears in the inserter but the editor UI is blank.

Minimum index.asset.php

<?php
return array(
    'dependencies' => array(
        'wp-blocks',
        'wp-element',
        'wp-block-editor',
        'wp-components',
        'wp-i18n',
    ),
    'version' => '1.0.0',
);

With Element Registry Dependencies

If the block calls window.wptElements.buildElementClasses(), declare wpt-element-registry and every individual element handle the block uses:

<?php
return array(
    'dependencies' => array(
        'wp-blocks',
        'wp-element',
        'wp-block-editor',
        'wp-components',
        'wp-i18n',
        'wpt-element-registry',      // always required when using any element
        'wpt-element-heading',       // declare every element the block uses
        'wpt-element-description',
        'wpt-element-button',
        'wpt-element-badge',
    ),
    'version' => '1.0.0',
);

Available wpt-element Handles

Only declare handles for elements the block actually uses.

Never include wp-primitives in the dependencies array. It is not a registered script handle in this context and causes the entire block to silently fail to load. The block validator warns on this specific pattern.