CalHeatMap.js

var cal = new CalHeatMap();

cal.init({
    itemSelector: $element,

    domain: "month",
    subDomain: "x_day",

    range: 3,

    cellSize: 20,
    cellPadding: 5,
    domainGutter: 20,

    start: new Date(2016, 0, 1),
    weekStartOnMonday: true,

    tooltip: false,
    subDomainTextFormat: "%d",

    displayLegend: true,
    legendVerticalPosition: "top",
    legendMargin: [0, 0, 20, 0],

    legendCellSize: 20,
    legendCellPadding: 5,
    legend: [1, 2, 3, 4],

    highlight: new Date(2016, 0, 1) // Highlight January 1st
});