Gutenberg Base Block

block.js

var wpddb = {}
wpddb.contentTag = 'p';
wpddb.contentClass = 'wpddb-content';

(function (blocks, editor, element) {
   var el = wp.element.createElement;
   var RichText = editor.RichText;

   blocks.registerBlockType('wpddb/promotion', {
      title: 'WPDDB Promotion',
      icon: 'universal-access-alt',
      category: 'layout',

      attributes: {
         content: {
            type: 'array',
            source: 'children',
            selector: '.' + wpddb.contentClass, // using specific selector
         },
      },

      edit: function (props) {
         var content = props.attributes.content;

         function onChangeContent(newContent) {
            props.setAttributes({content: newContent});
         }

         return el(
            'div', 
            {},
            [
               el('h1', {
                  key: 'heading1',
               }, 'Back end'),
               el(
                  RichText,
                  {
                     tagName: wpddb.contentTag,
                     value: content,
                     onChange: onChangeContent,
                     className: wpddb.contentClass,
                     key: 'body1',
                  }
               )
            ]
         );
      },
      save: function (props) {
         return el(
            'div',
            {tagName: wpddb.contentTag},
            [
               el('h1', {key: 'heading1'}, 'Front end.'),
               el(RichText.Content, {
                  value: props.attributes.content,
                  className: wpddb.contentClass,
                  key: 'body1',
               })
            ]
         );
      },
   });
}(
   window.wp.blocks,
   window.wp.blockEditor,
   window.wp.element,
));

wp-dev-depth-block.php

<?php
/**
* Plugin Name: WT Dev Depth Block
*/
if (!defined('WPDDB_PROMOTION_BLOCK_SCRIPT')) {
	define('WPDDB_PROMOTION_BLOCK_SCRIPT', 'wpddb-promotion');
}

function wpddb_block_init()
{
	wp_register_script(
		WPDDB_PROMOTION_BLOCK_SCRIPT, // the name of our block script
		plugins_url('block.js', __FILE__), // the javascript to be enqueued
		['wp-blocks', 'wp-element', 'wp-editor'] // dependencies
	);

	register_block_type('wpddb/promotion', [
		'editor_script' => WPDDB_PROMOTION_BLOCK_SCRIPT,
	]);
}
add_action('init', 'wpddb_block_init');