Binary search on a sorted array using recursion: https://jsbin.com/pilitor/edit?js,console

binary-search.js

// Task:
// Find an item in an sorted array.

var array = [1,3,4,6,7,8,8,9,10,56,102,200,230]
var item = 200

var globalCounter = 0


console.log(binarySearch(array,  item))
console.log("iterated " + globalCounter + " time/s.")


function binarySearch(array, item, leftIndex, rightIndex) {
  
  // Count "O" 
  globalCounter++
  
  if (leftIndex === undefined) leftIndex = 0;
  if (rightIndex === undefined) rightIndex = array.length - 1;
  
  
  var midIndex = leftIndex + Math.floor((rightIndex - leftIndex) / 2);

  
  if (leftIndex > rightIndex) {
    
    return false;
    
  }
    
  
  if (array[midIndex] === item) {
    
    return true;
    
  } else if (item < array[midIndex]) {
    
    return binarySearch(array, item, leftIndex, midIndex - 1);
    
  } else {
    
    return binarySearch(array, item, midIndex + 1, rightIndex);
    
  }
  
  
}