Currently, Steemit has no support for tag autocompletion when you write an story.
It is inconvenient. so I made a small extension script for Steemit.
You can use tag autocompletion after installing the script like the above image.
Here's how to install:
You need to install Tampermonkey before using my script.
Tampermonkey is very popular chrome extension that allows users to customize the site.
After installing Tampermonkey, you can install the script by clicking the link below.
Now, you can use the full power of the script.
The Source Code is available on my Github Gist
https://gist.github.com/appetizermonster/0f95597f1ad71b1668bc44812502605c
and here's the references:
https://github.com/selectize/selectize.js
https://github.com/steemit/steem-js
Thank you