VanillaJS is a joke, but a good one

The empty JavaScript library file

While you are learning to write javascript, you might come across this website.

http://vanilla-js.com/

if you tried to download the  javascript file, you will find it simply an empty file, no matter how many options you are selecting.

VanillaJS is the builtin JavaScript functions

The reasons is VanillaJS is just referring to the builtin JavaScript functions coming with modern browsers.

VanillaJS is high-performance

Before having the builtin support from browsers, we rely on libraries like jQuery and many other tools. Now we have VanillaJS, the high performance of it is one good reason for switching to it.