Web Socket between Javascript and Python
Maybe you need to deploy the website on your own server,because listening for client connecting is server side things,but the blogger.com host the server,the javascript section who provide to you is just for static pages.
If the blogger.com provide you api,that have some function like 
app.on("connection",function(){
/*send data to your python program*/
})
I have a blog on blogger.com, and they have a section where you can put html/javascript code in. I'm a total beginner to javascript/html but I'm somewhat adept at python. I want to open a listening socket on python(my computer) so that everytime a guest looks at my blog the javascript sends my python socket some data, like ip or datetime for example. I looked around on the internet, and ended up with the tornado module for my listening socket, but I have a hard time figuring out the javascript code. 
Basically it involves no servers.