line chart with ChartJS

HTML

<script src="http://www.chartjs.org/assets/Chart.min.js"></script>
<canvas id="chart" height="300" width="500"></canvas>

JavaScript

Chart.types.Bar.extend({
        name: "BarAlt",
        initialize: function (data) {
            var self = this;
            var originalBuildScale = self.buildScale;
            self.buildScale = function () {
                originalBuildScale.apply(this, arguments);

                var ctx = self.chart.ctx;
                var scale = self.scale;
                var originalScaleDraw = self.scale.draw;
                var barAreaWidth = scale.calculateX(1) - scale.calculateX(0);
                var barAreaHeight = scale.endPoint - scale.startPoint;
                self.scale.draw = function () {
                    originalScaleDraw.call(this, arguments);
                    scale.xLabels.forEach(function (xLabel, i) {
                        ctx.fillStyle = data.labelBackgrounds[i];
                        ctx.fillRect(
                            scale.calculateX(i - (scale.offsetGridLines ? 0.5 : 0)),
                            scale.startPoint,
                            barAreaWidth,
                            barAreaHeight);
                        ctx.fill();
                    })
                }
            }

            Chart.types.Bar.prototype.initialize.apply(this, arguments);
        }
    });


    var data = {
        labelBackgrounds: ["rgba(120,220,220,0.2)", "rgba(220,120,220,0.2)", "rgba(220,220,120,0.2)", "rgba(120,120,220,0.2)", "rgba(120,220,120,0.2)", "rgba(220,120,120,0.2)", "rgba(120,120,120,0.2)"],
        labels: ["January", "February", "March", "April", "May", "June", "July"],
        datasets: [
            {
                label: "My First dataset",
                fillColor: "rgba(220,220,220,0.8)",
                strokeColor: "rgba(220,220,220,0.8)",
                highlightFill: "rgba(220,220,220,0.75)",
                highlightStroke: "rgba(220,220,220,1)",
                data: [65, 59, 80, 81, 56, 55, 40]
            },
            {
                label: "My Second dataset",
                fillColor:...