JSFiddle - React, Tailwind, and code Playground

JavaScript

var x = [[1, 2, 3],[4, 5, 6],[7, 8, 9]];
var min,max;
x.forEach(function(itm) {
  itm.forEach(function(itmInner) {
    min = (min == undefined || itmInner<min) ? itmInner : min;
    max = (max == undefined || itmInner>max) ? itmInner : max;
  });
});
console.log(max,min); // 9, 1