Measure of Central Tendencies, mean-median-mode with NodeJs

statictics.js

/*
* Input
* The first line contains an integer, N, denoting the number of elements in the array.
* The second line contains N space-separated integers describing the array's elements.
* The should print mean, median and mode
*/
function processData(input) {
let lines = input.split("\n");
const n = parseInt(lines[0]);
let a = lines[1].split(" ");
a.sort(function (a, b) {  return a - b;  });
   
  //mean
let mean = 0, sum = 0;
for( let i=0; i<n; i++){
  sum += parseInt(a[i]);
}
mean = sum / n ;
    
  //median
let median = 0;
if(n % 2 === 0) {
  median = ( parseInt(a[n/2]) + parseInt(a[n/2 - 1]) )/2;
} else {
  median = a[Math.floor(n/2)];
} 

  //mode
  let set = new Set(a);
  let setsize = set.size ;
  let arrset = Array.from(set);
  let mode = a[0];
  if( n !== setsize) {
    let freq = [];  // Array(count)
    for(let i=0; i < setsize ; i++){
      let count = 0;
      for(let j=0; j<n ; j++) {
        if(arrset[i] === a[j]){
             count++
        }
          freq[i] = count;
      }
    }
    //mode = elt whose freq[index] is max
    freq.sort(function (a, b) {  return a - b;  });
    let max = freq[setsize-1];
    mode = indexof(max);
  }else{
        mode = a[0];
    }

  console.log(mean);
  console.log(median);
  console.log(mode);
  
  return 0;
}

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});