Incorrect filtering when using a Dimension that returns a Date from the accessor

[mtraynham]

There is some weirdness when using a Crossfilter dimension that has an accessor function that returns a Date object. It seems to work fine when using Bar Charts with brushing and range filtering, but not Row or Pie. The chart works fine when the accessor returns Date.getTime() (as this is now numeric), but then the labeling is hard to read.

It looks like too many things are being filtered (i.e. dc's baseMixin _filterHandler could improve the value checking, maybe using filter.valueOf()).

Here is a JSFiddle showing most of the weirdness:
http://jsfiddle.net/SjT8E/1/

In the Fiddle, charts 3 and 5 both use the date dimension accessor. Charts 4 and 6 are their Date.getTime() counterparts, respectively. Notice the differences in the other charts when filtering on 3 vs. 4 and 5 vs. 6.

[mtraynham]

So a fix for this, update the filter handler to use a valueOf comparison (like the one used in Crossfilter's quicksort)

From Crossfilter.js:
// Note that for value comparison, <, <=, >= and > coerce to a primitive via
// Object.prototype.valueOf; == and === do not, so in order to be consistent
// with natural order (such as for Date objects), we must do two compares.

An updated Fiddle showing off the fix:
http://jsfiddle.net/S96yD/

The changed baseMixin _filterHandler:

    var _filterHandler = function (dimension, filters) {
        dimension.filter(null);

        if (filters.length === 0)
            dimension.filter(null);
        else
            dimension.filterFunction(function (d) {
                for(var i = 0; i < filters.length; i++) {
                    var filter = filters[i];
                    if (filter.isFiltered && filter.isFiltered(d)) {
                        return true;
                    } else if (filter <= d && filter >= d) {
                        return true;
                    }
                }
                return false;
            });

        return filters;
    };

A diff patch:

Index: dc.js
===================================================================
--- dc.js   (revision 59169)
+++ dc.js   (working copy)
@@ -605,7 +605,7 @@
                     var filter = filters[i];
                     if (filter.isFiltered && filter.isFiltered(d)) {
                         return true;
-                    } else if (filter == d) {
+                    } else if (filter <= d && filter >= d) {
                         return true;
                     }
                 }

[mtraynham]

Also to add, and this was out of curiosity from Crossfilter's code, using:

filter <= d && filter >= d

is 98% faster in Firefox and 88% faster in Chrome than using:

filter.valueOf() == d.valueOf()

Based on this jsperf:
http://jsperf.com/compare-valueof-vs

[gordonwoodhull]

Fixed via #555 - thanks @mtraynham!