Edit in JSFiddle

var chart = new SmoothieChart({
  grid: { strokeStyle:'rgb(125, 0, 0)', fillStyle:'rgb(60, 0, 0)',
          lineWidth: 1, millisPerLine: 250, verticalSections: 11, },
  labels: { fillStyle:'rgb(255, 255, 255)' }
});
var timeSeries = new TimeSeries();
chart.addTimeSeries(timeSeries, { strokeStyle: 'yellow', lineWidth: 2 });
chart.streamTo(document.getElementById('chart'), 100);
setInterval(function()
{
    timeSeries.append(new Date().getTime(), Math.random());
}, 100);
document.getElementById('button').onclick = function()
{
    timeSeries.data = [];
};

<script src="http://smoothiecharts.org/smoothie.js"></script>

<div>
    <canvas id="chart" width="400" height="200"></canvas>
</div>

<button id='button'>Clear</button>