.js

const _ = require('underscore');
const machineData = [1,2,3,2,3,2,3,4,5,5,5,6,5,4,4,3,1];
const info = _.reduce(machineData, (memo, current, index) => {
  const { last, lastSlope, minIndexes, maxIndexes } = memo
  const slope = last ? current-last : 0;
  if (slope != 0 && lastSlope && Math.sign(slope) != Math.sign(lastSlope)) {
    if (slope > 0) {
      minIndexes.push(index-1);
    } else {
      maxIndexes.push(index-1);
    }
  }
  memo.lastSlope = slope == 0 ? memo.lastSlope : slope;
  memo.last = current;
  return memo;
}, {lastSlope: null, minIndexes:[], maxIndexes:[], last:null})