Replace error with DataTables

[Braunson]

Seems this works no problem:

    var table = $('#job-table-section').find('.dataTable');
    var dt = table.DataTable({
        'ajax':'/api/jobs/datatable'
    });

But once when I add parameters to the DataTables ajax call like so, I get the replace error below

    var table = $('#job-table-section').find('.dataTable');
    var dt = table.DataTable({
        'ajax': {
            'data':'/api/jobs/datatable',
            beforeSend: function(jqXHR, settings) {},
            complete: function(response, textStatus, jqXHR) {}
        }            
    });

The error with the above code:

Uncaught TypeError: Cannot read property 'replace' of undefined on lines 2253

Seems to be this function, but no info on where it's being used to cause the error:

    String.prototype.toProperCase = function() {
        return this.replace(/\w\S*/g, function(txt) {
            return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();
        });
    };

Specifically:

        return this.replace(/\w\S*/g, function(txt) {