Generic JS timer script for testing performance

jstimer.js

let averageOf = (array) => array.reduce((a, b) => a + b) / array.length;
let minOf = (array) => Math.min.apply(Math, array)
let maxOf = (array) => Math.max.apply(Math, array)

let request = {};
request.i = 1;
request.iterations = 1000;
request.tests = 10;

function timer(f, args) {
  args = args || {};
  var durations = [];
  for (x = 1; x <= request.tests; x++) {
    var startTimer = new Date().getMilliseconds();
    for (request.i = 1; request.i <= request.iterations; request.i++) {
      f.apply(this, args);
    }
    durations.push(new Date().getMilliseconds() - startTimer);
  }
  console.log(f.name + "\n" +
    "range(ms): " + minOf(durations) + "-" + maxOf(durations) + "\n" +
    "average: " + averageOf(durations));
}

function a() {
}

function b() {
}

timer(a);
timer(b);