Sales by Match (Number of pairs in an Array)

function sockMerchant(n, ar) {
    // Write your code here
    var newArr = ar.sort();
    var count = 0;
    for(let j=0;j<newArr.length-1;j++){
        if(newArr[j]===newArr[j+1]){
            j++;
            count += 1;
        }
    }
    return count;
}