Vanilla javascript is only and plain javascript, The original Javascript. It means any code of javascript is written without using javascript framework or libraries like JQuery, React, Angular JS, Node JS etc.
If you write javascript code using any of its libraries than it is not vanilla javascript. vanilla javascript refers to ES5/6/7.
Vanilla javascript also referred as vanilla js and javascript as js.
Advantages of Vanilla javascript
Simple and easy to use
Because of originality and similar syntax like c and c++, it is easy to learn and implement.
Lightweight
Because of pure and raw form of javascript. it becomes easy to implement and modify.
Execution speed
Framework or libraries finally converted in javascript code. So, vanilla Javascript is fast in execution then other javascript libraries
No dependency
Framework or libraries are maintained by community or companies so there is huge dependency, vanilla js is a standard language, hence no dependency.