C3 js line chart getting error for date

I am trying to use c3.js timeseries line chart (URL : http://c3js.org/samples/timeseries.html). The only difference being that I am using the CDN link to the js files instead of downloading them. However I keep getting the following error

Chrome Uncaught Error: x is not defined for id = "date".

Firefox Error: x is not defined for id = "date".

throw new Error('x is not defined for id = "' + id + '".'); | ------------+

The html file is given below

<!DOCTYPE html>
<html>
<meta charset="utf-8">
<head>

<link rel="stylesheet" type="text/css" href="http://cdnjs.cloudflare.com/ajax/libs/c3/0.4.10/c3.css"/>

<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/c3/0.4.10/c3.js"></script>

<script>
    var dates = ['20130101', '20130102', '20130103', '20130104', '20130105', '20130106'];
    var sample = [30, 200, 100, 400, 150, 250];

    var chart = c3.generate({
        bindto: '#chart',
        data: {
                x:'Dates',
                x_format:'%Y%m%d',
        columns: [
        //['Dates'].concat(dates),
        //['Sample'].concat(sample)
                ['date', '20130101', '20130102', '20130103', '20130104', '20130105', '20130106'],
                ['sample', 30, 200, 100, 400, 150, 250]
                ]
        },
        axis: {
                x: {
                    type : 'timeseries'
                }
        }
    });
</script>
</head>
<body>
    <div id="chart"></div>
</body>
</html>

I am not sure why I am getting the date related errors. I tried using actual data values in the C3 arguments as well as passing the data as variables. Any help is highly appreciated

Solution

Your dates array needs a first value with the name/id of the 'set', such as:

var dates = ['Dates', '20130101', '20130102', '20130103', '20130104', '20130105', '20130106'];

The data object's x property needs to match this. In the code above you've got differing values: Dates and date.

data: { x:'Dates',

You were closer with the concat attempt.

See this link: http://jsfiddle.net/jrdsxvys/16/