Migratory Ranks Javascript solution

26 Jul 2019

In between looking at React I have been taking a look at some of the coding tasks on HackerRank mostly to help get a handle of a lot of the new functional Javascript functionality I have not used since classic ASP days. So here I make use of the sort method and the new Map object. The Map object in particular had difficulty in identifying ‘undefined’. In the end I found the ‘has’ method and came up with the below solution.

 function migratoryBirds(arr) {

    let bMap = new Map();
    let sarr = arr.sort(function (a, b) { return a - b });
    var curval = 1;
    for (var i = 0; i < sarr.length; i++) {

        if (bMap.has(sarr[i])) {

            curval = bMap.get(sarr[i]);
            bMap.set(sarr[i], curval + 1);
        else {
            bMap.set(sarr[i], 1);

    let maxval = bMap.get(sarr[0]);
    let minkey = sarr[0];

    bMap.forEach(function (value, key) {
        if (maxval < value) {
            maxval = value;
            minkey = key;

    /*return Array.from(bMap);*/
    return minkey

Published on 26 Jul 2019 Find me on Twitter!