Horloge JS

let doc;

window.onload = function() {
  doc = document.getElementById('heure');
  doc.classList.add('heureCl')
}

function update()
{
  if (doc)
  {
    let date = new Date();
    let hr = date.getHours() < 10 ? "0"+ date.getHours() : date.getHours();
    let min = date.getMinutes() < 10 ? "0"+ date.getMinutes() : date.getMinutes();
    let sec = date.getSeconds() < 10 ? "0"+ date.getSeconds() : date.getSeconds();
    doc.innerHTML = hr + ":" + min + ":" + sec;
  }
}
window.setInterval(update, 1000);