The min() operator is pretty much the opposite of the max() operator; it comes in two flavors: with parameter and without parameter. Its task is to find the smallest value. To use it, type:
// mathematical/min.js
let streamOfValues$ = Rx.Observable
.of(1, 2, 3, 4)
.min();
// emits 1
streamOfValues$.subscribe(data => console.log(data));