Generar graficos canvas con js

buenas a todos
en esta oportunidad les presento como hacer graficos con Chart.js

Ejemplo


Código

<script src="../../js/jquery.js"></script>
<script type="text/javascript" src="http://www.chartjs.org/assets/Chart.js"></script>


  <style type="text/css">
     #chartjs-tooltip {
     opacity: 0;
     position: absolute;
     background: rgba(0, 0, 0, .7);
     color: white;
     padding: 3px;
     border-radius: 3px;
     -webkit-transition: all .1s ease;
     transition: all .1s ease;
     pointer-events: none;
     -webkit-transform: translate(-50%, 0);
     transform: translate(-50%, 0);
 }
  </style>

 <canvas id="migrafico" width="400" height="200"></canvas>
<div id="chartjs-tooltip"></div>
<script type='text/javascript'>//<![CDATA[
var ctx = $("#migrafico").get(0).getContext("2d");

var data = {
    labels: ["enero", "febrero", "marzo", "abril", "Mayo", "junio", "julio"],
    datasets: [{
        label: "My First dataset",
        fillColor: "rgba(220,220,220,0.2)",
        strokeColor: "rgba(220,220,220,1)",
        pointColor: "rgba(220,220,220,1)",
        pointStrokeColor: "#fff",
        pointHighlightFill: "#fff",
        pointHighlightStroke: "rgba(220,220,220,1)",
        data: [65, 59, 80, 81, 56, 55, 40]
    }]
};

var myLineChart = new Chart(ctx).Line(data, {
    customTooltips: function (tooltip) {
        var tooltipEl = $('#chartjs-tooltip');
        
        if (!tooltip) {
            tooltipEl.css({
                opacity: 0
            });
            return;
        }
        
        tooltipEl.removeClass('above below');
        tooltipEl.addClass(tooltip.yAlign);
        
        // split out the label and value and make your own tooltip here
        var parts = tooltip.text.split(":");
        var innerHtml = '<span>' + parts[0].trim() + '</span> : <span><b>' + parts[1].trim() + '</b></span>';
        tooltipEl.html(innerHtml);
        
        tooltipEl.css({
            opacity: 1,
            left: tooltip.chart.canvas.offsetLeft + tooltip.x + 'px',
            top: tooltip.chart.canvas.offsetTop + tooltip.y + 'px',
            fontFamily: tooltip.fontFamily,
            fontSize: tooltip.fontSize,
            fontStyle: tooltip.fontStyle,
        });
    }
});
//]]> 

</script>

</body>

</html>

Espero que sea de ayuda :)