Get frequency of committed time, in UTC hours

hours.js

'use strict';
const child_process = require('child_process');
const log = child_process.spawnSync('git', ['log', '--format=%cI', '-n', '10000'], {
  cwd: process.cwd()
});
const dates = log.stdout.toString().trim();
const hours = dates.split('\n').map(d => new Date(d).getUTCHours());
const map = new Map();
for (const h of hours) {
  if (map.has(h)) {
    map.set(h, map.get(h) + 1);
  } else {
    map.set(h, 1);
  }
}
const pairs = [...map.entries()].sort((a, b) => a[1] > b[1] ? -1 : 1);
console.log(pairs);