For example, there are n=7 socks with colors ar=[1,2,1,2,1,3,2]. There is one pair of color 1 and one of color 2.

function sockMerchant(n, ar) {
  //Need to initiate a count variable to count pairs and return the value
  let count = 0
  //sort the given array
  ar = ar.sort()
  //loop through the sorted array 
  for (let i=0; i < n-1; i++) {
    //if the current item equals to the next item 
    if(ar[i] === ar[i+1]){
      //then that's a pair, increment our count variable
      count++
      //also increment i to skip the next item
      i+=1
    }
  }
  //return the count value
  return count
}