plotjs

<script src="http://www.michalpaszkiewicz.co.uk/plotjs/plotjs.js"></script>

pie chart

 var data = {
 bob: 3,
 jane: 5,
 x: 4,
 "Some random value": 32,
 y: 81
 }
 var options = {};
 var pie = new Plot.Pie("my-pie", data, options);

bar chart

var data = {
 bob: 3,
 jane: 5,
 x: 4,
 "lots of yellow frogs with jumpers": 32,
 y: 81
}
var options = {};
//pie chart
var pie = new Plot.Pie("my-pie", data, options);
//bar chart
var bar = new Plot.Bar("my-bar", data, options);
bar.data = pie.data;
bar.draw(bar);

scatter plot

var xyData = { values: [], colour: "red" };
for (var i = -200; i < 200; i++) {
 xyData.values.push({ x: i, y: 4 * Math.sin(i / 20) - 2 * Math.cos( i / 10)});
}
var scatter = new Plot.Scatter("my-scatter", xyData, options);
scatter.addCurve(function (i) { return 2 * Math.sin(i / 20) - Math.cos(i / 8) }, "orange");

box and whisker diagram

var xData = [{ values: [], colour: "red" }, { values: [], colour: "blue" }, { values: [], colour: "green" }];
for (var i = 0; i < 20; i++) {
 xData[0].values.push({ x: i * 2 + 5 });
 xData[1].values.push({ x: i / 2 + 12 });
 xData[2].values.push({ x: i * i / 20 + 10 });
}
var boxAndWhisker = new Plot.BoxAndWhisker("my-box-and-whisker", xData, options);