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Well thanks. That works.

crossorigin = "" does not seem to do anything, and this works with either http and https.

<html>
<script src="https://unpkg.com/dsteem@^0.8.0/dist/dsteem.js"></script>
<script type="text/javascript">
var client2 = new dsteem.Client('http://testnet.steemitdev.com');
  client2.call('condenser_api', 'get_dynamic_global_properties'
               ).then(function(err, response){
                   console.log(err, response);
   });       
</script>
</html>

The above works fine.

So I assume condenser works, but app base does not ?

.

that @0.8.0 is just an artifact - I copied those lines from somewhere.
I am not very familiar with dsteem or JS in general, either.

How do you get beem to work, then ?

from beem.blockchain import Blockchain
from beem import Steem
from beem.instance import set_shared_steem_instance

blockchain = Blockchain()
print(blockchain.get_current_block_num())

testnet = Steem(node=["https://testnet.steemdev.com:2001"])
set_shared_steem_instance(testnet)

blockchain2 = Blockchain()
print(blockchain2.get_current_block_num())

This does not work either, I tried variations of the url with port and without and http https ...