SOURCE

let arr =[
                [850, 740, 900, 1070, 930, 850, 950, 980, 980, 880, 1000, 980, 930, 650, 760, 810, 1000, 1000, 960, 960],
                [960, 940, 960, 940, 880, 800, 850, 880, 900, 840, 830, 790, 810, 880, 880, 830, 800, 790, 760, 800],
                [880, 880, 880, 860, 720, 720, 620, 860, 970, 950, 880, 910, 850, 870, 840, 840, 850, 840, 840, 840],
                [890, 810, 810, 820, 800, 770, 760, 740, 750, 760, 910, 920, 890, 860, 880, 720, 840, 850, 850, 780],
                [890, 840, 780, 810, 760, 810, 790, 810, 820, 850, 870, 870, 810, 740, 810, 940, 950, 800, 810, 870]
            ]

console.log(prepareBoxplotData(arr))


function prepareBoxplotData (rawData, opt) {
      opt = opt || {};
      var boxData = [];
      var outliers = [];
      var axisData = [];
      var boundIQR = opt.boundIQR;
      var useExtreme = boundIQR === 'none' || boundIQR === 0;

      for (var i = 0; i < rawData.length; i++) {
        axisData.push(i + '');
        var ascList = asc(rawData[i].slice());
        var Q1 = quantile(ascList, 0.25);
        var Q2 = quantile(ascList, 0.5);
        var Q3 = quantile(ascList, 0.75);
        var min = ascList[0];
        var max = ascList[ascList.length - 1];
        var bound = (boundIQR == null ? 1.5 : boundIQR) * (Q3 - Q1);
        var low = useExtreme ? min : Math.max(min, Q1 - bound);
        var high = useExtreme ? max : Math.min(max, Q3 + bound);
        boxData.push([low, Q1, Q2, Q3, high]);

        for (var j = 0; j < ascList.length; j++) {
          var dataItem = ascList[j];

          if (dataItem < low || dataItem > high) {
            var outlier = [i, dataItem];
            opt.layout === 'vertical' && outlier.reverse();
            outliers.push(outlier);
          }
        }
      }

      return {
        boxData: boxData,
        outliers: outliers,
        axisData: axisData
      };
    }

    function asc(arr) {
      arr.sort(function (a, b) {
        return a - b;
      });
      return arr;
    }

    function quantile(ascArr, p) {
      var H = (ascArr.length - 1) * p + 1;
      var h = Math.floor(H);
      var v = +ascArr[h - 1];
      var e = H - h;
      return e ? v + e * (ascArr[h] - v) : v;
    }