Find worst case time complexity of function

Is my calculation of the following function correct or not ?  Thx

T= 4+ 2(n+1) + n/2
  = 4+ 2n+2 +log(n)
  = 2n +log (n) + 6
  ≥ 2log(n) + log(n) +6
  ≥ 3log(n) + 6
  ≥ log(n)+2

So the time complexity is O(log n).




function Search(array, item) {

   let minIndex = 0;
   let maxIndex = array.length
   let currentIndex;
   let currentElement;                

   while (minIndex <= maxIndex) {      
      currentIndex = Math.floor((minIndex + maxIndex) / 2);
      currentElement = array[currentIndex];

      if (currentElement < item) {
         minIndex = currentIndex + 1;
      }
      else if (currentElement > item) {
         maxIndex = currentIndex - 1;
      }
      else {
         return currentIndex;
      }
   }
}