Essentially you'd have an emoji icon next to the text field for submitting a message, and when you click on that icon, a pop-up modal would come up!

Here's a summarised version of how it'd basically work:

1. The modal would grab the list from MediaWiki:Smileys and display each icon visually.
2. Then you would click on the emoji you want to use :D
3. Once it's clicked, it appears in the textbox. Whenever you're ready to submit your message, just press enter, tada!

Basic & rough concept demo at: http://s.codepen.io/SamanthaNguyen1116/debug/oLKyrq