How to get average to work with numbers that have a comma

smason

Consider the following snippet inside a footer callback.

"footerCallback": function(row, data, start, end, display) {
  var api = this.api();
api.columns('.avg', {
                page: 'current'
          }).every(function() {
                var avg = this.data().average();
                avg = avg.toFixed(2);

         $(this.footer()).html("" + avg + "%");
          });

It seems to return NaN if a value in one of the cells it's looking at contains a comma. How do I remove the comma so that the average function works correctly?

kthorngren

You could use the replace function similar to this example:
https://datatables.net/examples/advanced_init/footer_callback.html

Kevin

smason

I modified the intVal function to my needs, just to remove the comma.
Calculating the average was a little tricky because you have to get the length of the dataset as the denominator. Maybe this could help someone else too.

        "footerCallback": function(row, data, start, end, display) {
                 var api = this.api();

                // Remove the comma to get data for summation
                var intVal = function ( i ) {
                    return typeof i === 'string' ?
                        i.replace(/,/g,'')*1 :
                            typeof i === 'number' ?
                                       i : 0;
                };

    api.columns('.avg', {
                page: 'current'
              }).every(function() {

            var numerator = this
                        .data()
                        .reduce( function(a, b) {
                                return (intVal(a) + intVal(b));
                        }, 0);

            var denominator = this.data().length;

            avg = numerator / denominator;
            avg = avg.toFixed(2)

            $(this.footer()).html(avg);
        });