list_blocks.js

/* gets all available blocks and log them in console */
wp.data.select( "core/blocks" ).getBlockTypes().forEach(function(element) {
  console.log(element['name']);
});


/* same thing but in a new window and formatted for php */
var win = window.open("", "Title", "toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=780,height=200,top="+(screen.height-400)+",left="+(screen.width-840));
var tmpContent = 'Block List<br><hr><br>array(<br>';
wp.data.select( "core/blocks" ).getBlockTypes().forEach(function(element) {
  tmpContent = tmpContent + "'" + element['name'] + "',  //"+element['description']+"<br>";
});
tmpContent = tmpContent + ');';
win.document.body.innerHTML = tmpContent;