has this neat function that you just have to hit the "T" key twice to make a popover appear where you can add tags, for example here:

I don't have enough experience with JavaScript to find out how they implemented this, so I wanted to ask here if anyone knows a tutorial which explains how to implement a feature like this. The popover itself isn't a problem, I just need a way to capture when the user hits "tt" and then a JavaScript function has to be called.