<script>
	var coworkers = ["james", "tim"];
  coworkers.push("kevin");
  document.write(coworkers[0]);
  document.write(coworkers.length);
</script>

<script>
	var coworkers = ["james", "tim", "kevin"];
</script>
<ul>
  <script>
  	var i = 0;
    while (i < coworkers.length){
      document.write('<li>'+coworkers[i]+'</li>');
      i = i + 1;
    }
  </script>
</ul>

<input type="button" value="night" onclick="
        if(this.value === 'night'){
            document.querySelector('body').style.backgroundColor = 'black';
            document.querySelector('body').style.color = 'white';
            this.value = 'day';

            var alist = document.querySelectorAll('a');
            var i = 0;
            while (i < alist.length){
                alist[i].style.color = 'powderblue';
                i = i + 1; 
            }
        } else{
            document.querySelector('body').style.backgroundColor = 'white';
            document.querySelector('body').style.color = 'black';
            this.value = 'night';

            var alist = document.querySelectorAll('a');
            var i = 0;
            while (i < alist.length){
                alist[i].style.color = 'blue';
                i = i + 1; 
            }
        }
    ">