binarySearch.js

/* Binary search algorithm implementation */
function binarySearch(items,valueToFind){
  let start = 0
  let stop = items.length-1
  let middle = Math.floor( (start+stop) / 2 ) 
  let itemFoundAtPos = -1
  
  while( start < stop ){
    let itemInMiddlePos = items[middle]
    
    if(itemInMiddlePos === valueToFind){
      itemFoundAtPos = middle;
      break
    }
    
    if(valueToFind < itemInMiddlePos ){
       stop = middle -1
    }else{
      start = middle +1
    }
    
    middle =  Math.floor( (start+stop) / 2 ) 
    
  }

  if(items[middle] === valueToFind){
    return middle
  }
  
  return itemFoundAtPos;
  
}