Prints a cadence table for pace-'body height'-relations to gain optimal hip extension

cadence.js

#!/usr/bin/node

const bodyHeightCmArg = process.argv[2];
const paceArg = process.argv[3];

function printUsage() {
  console.log(`Cadence calculator - Print cadence for specific paces and body height to gain optimal hip extension
  
Usage:
  ./cadence.js bodyHeightInCm [paceMinKm]
  
Example:
  ./cadence.js 177
  ./cadence.js 177 4:00`);
  process.exit();
}

function calcCadence(speedKmh, bodyHeightCm) {
  return Math.ceil(160 + (speedKmh - 6) * 2.5 - (bodyHeightCm - 170) / 2);
}

function speedToPace(speedKmh) {
  const pace = 60 / speedKmh;
  const minuten = Math.floor(pace);
  const sekunden = Math.floor((pace - minuten) * 60).toString();
  return `${minuten.toString().padStart(2, '0')}:${sekunden.padStart(2, '0')}`;
}

function paceToSpeed(paceString) {
  const [minutes, seconds] = paceString.split(':');
  if (minutes == null || seconds == null) {
    throw new Error(`Incorrect pace argument: ${paceString}`);
  }
  return 60 / (parseInt(minutes, 10) + parseInt(seconds, 10) / 60);
}

if (bodyHeightCmArg == null) {
  printUsage();
}
if (paceArg != null) {
  try {
    paceToSpeed(paceArg);
  } catch (error) {
    console.log(error);
    printUsage();
  }
}

const bodyHeight = parseInt(bodyHeightCmArg, 10);

console.log(`Pace   Cadence   Body height: ${bodyHeight}cm`);

if (paceArg != null) {
  console.log(`${speedToPace(paceToSpeed(paceArg))}  ${calcCadence(paceToSpeed(paceArg), bodyHeight)}`);
} else {
  for (let speed = 7; speed <= 23; speed += 0.4) {
    console.log(`${speedToPace(speed)}  ${calcCadence(speed, bodyHeight)}`);
  }
}