Example of how to use registerBlockType() to create a custom block in WordPress https://wp.zacgordon.com/2017/12/28/how-to-use-to-registerblocktype-to-create-blocks-in-wordpress/

registerBlockType-example.js

// Get helper functions from global scope
const { registerBlockType } = window.wp.blocks;
const { __ } = window.wp.i18n;

// Use registerBlockType to create a custom block
registerBlockType(
  'example-plugin/example-custom-block',
  {
    // Localize title using wp.i18n.__()
    title: __( 'Block Title' ),
    // Category Options: common, formatting, layout, widgets, embed
    category: 'common',
    // Dashicons Options - https://goo.gl/aTM1DQ
    icon: 'wordpress-alt',
    // Limit to 3 Keywords / Phrases
    keywords: [ 
      __( 'Example' ), 
      __( 'Project' ), 
      __( 'Code Samples' ) 
    ],
    // Attributes set for each piece of dynamic data used in your block
    attributes: {
      exampleContent: {
        type: 'array',
        source: 'children',
        selector: 'div.my-content',
      },
    },
    // Determines what is displayed in the editor
    edit: props => {
      const onChangeContent = value => {
        props.setAttributes( { exampleContent: value } );
      };
      return (
        <div className={props.className}>
          <Editable
            tagname="div"
            multiline="p"
            className="my-content"
            placeholder={ __( 'Add your content...' ) }
            value={props.attributes.exampleContent}
            onChange={onChangeContent}
          />
        </div>
      );
    },
    // Determines what is displayed on the frontend
    save: props => {
      return (
        <div className={props.className}>
          {props.attributes.exampleContent}
        </div>
      );
    },
  },
);