Another early Kata revist

OK I know I’ve been promising you more about ‘this’  and I will come back to it in my next post.

So with this kata I had to write a processArray function which would take an array and a callback function as parameters.  The callback function would be applied to every element in the array. So for example:

Array [4, 8, 2, 7, 5] after processing with function

var myArray = [4, 8, 2, 7, 5];

myArray = processArray(myArray,function (a) {

                 return a * 2;


//will be [ 8, 16, 4, 14, 10 ].


Array [7, 8, 9, 1, 2] after processing with function

var myArray = [7, 8, 9, 1, 2];
myArray = processArray(myArray, function (a) {
                     return a + 5;
//will be [ 12, 13, 14, 6, 7 ].

I did this:

function processArray(arr, callback) {

                      var arrMine =[];

                      for (var i=0; i<arr.length; i++) {



                       return arrMine;


So I thought this was not a bad I had all the bases covered with this solution and it was not as messy as last time.  However I did not even consider the map function, something I had come across but not even considered.  This was the most upvoted solution.


function processArray(arr, callback) {



Once again simple elegant and much less code than mine.  While that was good, this just blew me away:

const processArray = (a, fn) =>;

One word – WOW!  I don’t even know where to begin.  I looked at it for a while and thought will I get to a level like that, I think I may do but it will be a while.  The journey continues


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