This is an early draft of Δt
Package delta-t (Δt) provides a class that you can use to create instances of deltas. Deltas are differences in values, for default it is difference in time (performance.now() with Date.now() fallback)
Example1: keeping track of time passed between frames.
const Δ = require('delta-t');
Δt = new Δ();
setInterval(function(){
Δt.update();
console.log(Number(Δt));
},17);