Gutenberg editor check in JS if specific block is active

Question

I am registering a block with custom JS in the editor:

function my_block_assets() {

  wp_register_script(
    'my-block-js', // 
    plugins_url( '/dist/my-block.js', dirname( __FILE__ ) ),
    array( 'jquery' ),
  );

  register_block_type(
    'custom/my-block', array(
      'style'         => 'my-block-css',        
      'editor_style'  => 'my-block-editor-css',
      'editor_script' => 'my-block-js',
    )
  );

}

add_action( 'init', 'my_block_assets' );

I want to run my custom JS only if the custom block is added in the editor. I am doing like this:

$(window).on('load', function () {      
  var container = document.querySelector('.wp-block-custom-my-block');

  if ( container ) {
    // run custom js
  }
});

This seems to work but may be slow. Is there any special JS function I can use to check if a block is added in the editor? I found ways to check for a block in PHP on the frontend using has_block() but nothing for JS in the editor.

Answer 1

You can select many block specific data from the Block Data Module. That said, the following works in the backend:

if ( wp.data.select('core/blocks').getBlockType('custom/my-block') ) { 
  //run custom js 
}

Doc of getBlockType.

Concerning the Frontend, I am going with the has_block function:

<?php 
mycustomblock_frontend_scripts() {
    if ( has_block( 'custom/my-block' ) ) {
        wp_enqueue_script('my-block-frontend-script');
    }
}
add_action( 'wp_enqueue_scripts', 'blockgallery_frontend_scripts' );