Edit in JSFiddle

var areachart = c3.generate({
  bindto: "#areachart",
  data: {
    columns: [
      ['data1', 300, 350, 300, 190, 50, 25],
      ['data2', 130, 100, 140, 200, 150, 50]
    ],
    types: {
      data1: 'area-spline',
      data2: 'area-spline'
    }
  }
});

<div id="areachart"></div>