Time complexity of the algorithm - JavaScript

Question

I need to count time complexity of this program. The program counts number of occurrences in a sorted array. Code is in JS.
I need three steeps to this task:

1. Dominant(elementary) operation
2. Complexity function(worst case)
3. The order of complexity in the worst case

May someone help me with it?

function count(tab, w, n)
  {
  //index of the first appearance
  idMin = first(tab, 0, n-1, w, n);
  
  //if 'w' doesn't exists in tab
  if (idMin == -1) { return idMin };
  
  //index of the last appearance
  idMax = last(tab, idMin, n-1, w, n);
  how_many = idMax-idMin+1;
  //return number of occurrences
  return how_many;
  }
    
function first(tab, l, p, w, n) //index of the first appearance
  {
  if (l <= p)                  //l - beginning index of the searching list, p - last index od the searching list
    {
    mid = Math.floor((l+p)/2); //middle index
    
    if ((mid == 0 || w  > tab[mid-1])&&(tab[mid] == w)) //mid == 0 when tab has one element
      {
      return mid; 
      }
    else if(w > tab[mid])
      {
      return first(tab, (mid+1), p, w, n);
      }
    else
      {
      return first(tab, l, (mid-1), w, n);
      }
    }
  return -1;
  }
    
function last(tab, l, p, w, n)//index of the last appearance
  {
  if (l <= p)
    {
    mid2 = Math.floor((l+p)/2);
    
    if ((mid2 == n-1 || w < tab[mid2+1]) && (tab[mid2] == w))
      {
      return mid2; 
      }
    else if (w < tab[mid2])
      {
      return last(tab, l, (mid2-1), w, n);
      }
    else
      {
      return last(tab, (mid2+1), p, w, n);
      }
    } 
  //return -1; it is necessary?
  }

var tab = [1, 2, 3, 3, 4, 5, 6, 7, 7, 7, 8, 9]
  , w   = 7           // looking value
  , n   = tab.length // length of the tab
  ;
counts = count(tab, w, n); 
document.write("Number " + w + " occurred " +counts+ " times<br/>");

question from:https://stackoverflow.com/questions/65939215/time-complexity-of-the-algorithm-javascript

Answer 1

Waitting for answers