Calculating median - javascript -

i've been trying calculate median still i've got mathematical issues guess couldn't correct median value , couldn't figure out why. here's code;

class statscollector {      constructor() {         this.inputnumber = 0;         this.average = 0;          this.timeout = 19000;          this.frequencies = new map();         (let of array(this.timeout).keys()) {             this.frequencies.set(i, 0);         }     }      pushvalue(responsetimems) {         let req = responsetimems;         if (req > this.timeout) {             req = this.timeout;         }          this.average = (this.average * this.inputnumber + req) / (this.inputnumber + 1);          console.log(responsetimems / 1000)         let groupindex = math.floor(responsetimems / 1000);         this.frequencies.set(groupindex, this.frequencies.get(groupindex) + 1);          this.inputnumber += 1;     }      getmedian() {         let medianelement = 0;         if (this.inputnumber <= 0) {             return 0;         }         if (this.inputnumber == 1) {             return this.average         }         if (this.inputnumber == 2) {             return this.average         }         if (this.inputnumber > 2) {             medianelement = this.inputnumber / 2;         }          let mincumulativefreq = 0;         let maxcumulativefreq = 0;         let cumulativefreq = 0;         let freqgroup = 0;         (let of array(20).keys()) {             if (medianelement <= cumulativefreq + this.frequencies.get(i)) {                 mincumulativefreq = cumulativefreq;                 maxcumulativefreq = cumulativefreq + this.frequencies.get(i);                 freqgroup = i;                 break;             }             cumulativefreq += this.frequencies.get(i);         }          return (((medianelement - mincumulativefreq) / (maxcumulativefreq - mincumulativefreq)) + (freqgroup)) * 1000;     }      getaverage() {         return this.average;     }  } 

here's snapshot of results when enter values of

342,654,987,1093,2234,6243,7087,20123

the correct result should be;

median: 1663.5

change median method this:

function median(values){     values.sort(function(a,b){     return a-b;   });    if(values.length ===0) return 0    var half = math.floor(values.length / 2);    if (values.length % 2)     return values[half];   else     return (values[half - 1] + values[half]) / 2.0; } 

fiddle