Something.js adds something
variable that equals different global properties every time you try to get its value.
<script src="something.js"></script>
npm install something
require('smth');
And now just use something!
console.log(typeof something) //'function'
console.log(typeof something) //'object'
console.log(typeof something) //'boolean'
console.log(typeof something) //'object'
console.log(typeof something) //'null'
Also you can compare your variables with something:
if(myVariable === something){
//...your code
}