formulaegyjs/main.js

$(document).ready(function () {
  $('.navbar-nav li').click(function (x) {
    $('.navbar-nav li').removeClass('active')
    $(event.target).parent().addClass('active')
  })
})

const circuits = {
  'HUN': {
    img: 'hungaroring.jpg',
    l: 4.381,
  },
  'MON': {
    img: 'monaco.jpg',
    l: 3.337,
  },
  'BEL': {
    img: 'spa.jpg',
    l: 7.004,
  },
  'ITA': {
    img: 'monza.jpg',
    l: 5.793,
  },
}

function showCircuit() {
  /** @type {HTMLImageElement} */
  const img = document.getElementById('circuitimage-img')
  /** @type {HTMLSelectElement} */
  const circuit = document.getElementById('circuit')
  img.src = './img/' + circuits[circuit.value].img
}

//---------------------------------------------------------

function calculate() {
  showCircuit()
  /** @type {HTMLSelectElement} */
  const circuit = document.getElementById('circuit')
  /** @type {HTMLInputElement} */
  const laptime = document.getElementById('laptime')
  /** @type {HTMLInputElement} */
  const output = document.getElementById('averagespeed')
  /** @type {number} */
  if (!circuit.value || !laptime.value) { return }
  const l = circuits[circuit.value].l
  const t = laptime.valueAsNumber
  output.value = Math.round(l / (t / 3600)) + ' km/h'
}