Cal heatmap show nan value other color

Question

Can cal heatmap.js let NaN value represent another color?

Now if my data has NaN, it will only be represented as 0.

 var cal = new CalHeatMap();

        cal.init({
            itemSelector: "#cal-heatmap",
            itemName: ["μm<br/>", "μm"],
            displayLegend: false,
            cellSize: 20,
            tooltip: true,
            data: data,
            start: new Date(new Date().getFullYear(), new Date().getMonth() , new Date().getDate()-15),
            domain: "day",          // Group data by month
            subDomain: "hour",          // Split each month by days
            legend: [0, 20, 40, 60, 80, 100],
            subDomainTextFormat: "%-H",
            legendCellSize: 15,
            browsing: true,
            nextSelector: "#domain-highlight-next-selector",
            previousSelector: "#domain-highlight-previous-selector",
            rowLimit: 12,
            range: 16,

        });