var array = [1,2,3,4,5]

let recursiveFunction = function(array,x,start,end){
   if(start > end){
   return false
   }
   let mid = Math.floor((start + end)/2)
   if(array[mid] === x){
   return true;
   }
   
   if(array[mid] > x){
     return recursiveFunction(array,x,start,mid-1);
   }
   else{
     return recursiveFunction(array,x,start+1,end);
   }
}

console.log(recursiveFunction(array,6,0,array.length))