Extending WP Core Blocks

Hi there,
I am trying to extend WP Core Blocks by following this tutorial (https://jeffreycarandang.com/extending-gutenberg-core-blocks-with-custom-attributes-and-controls/). I have created a js file and added the script. Unfortunately, I am getting all these errors in the console. Do I need to use react js to extend WP Core Blocks?

Thanks!