text: //function expression to select element
  
  const selectElement = (s) => document.querySelector(s);
  
  
  //open the menu on click
  
  selectElement('.open').addEventListener('click',()=>{
     selectElement('.nav-list').classList.add('active');
  });
  
  
  //close the menu on click
  
  selectElement('.close').addEventListener('click',()=>{
     selectElement('.nav-list').classList.remove('active');
  });
  
  
  //for clock
  function clock(){
      var hour=document.getElementById('hour');
      var min=document.getElementById('min');
      var sec=document.getElementById('sec');
      var h=new Date().getHours();
      var m=new Date().getMinutes();
      var s=new Date().getSeconds();
      h =(h < 10) ? "0" + h : h
      m =(m < 10) ? "0" + m : m
      s =(s < 10) ? "0" + s : s
      
      hour.innerHTML=h;
      min.innerHTML=m;
      sec.innerHTML=s;
  }
  var interval = setInterval(clock,1000);