Chartjs-Draw line charts by days/weeks/months from a timestamp

Highstock provides dataGroupig functionality that seems to be what you’re looking for.

Live demo: http://jsfiddle.net/kkulig/avd0gqgr/

I forced data grouping and overwrote its units on button click.

//options
  xAxis: {
    ordinal: false
  },

  plotOptions: {
    series: {
      dataGrouping: {
        forced: true,
        approximation: 'sum'
      }
    }
  },
(...)

// button
$('#months').click(function() {
  chart.update({
    plotOptions: {
      series: {
        dataGrouping: {
          units: [
            [
              'month', [1]
            ]
          ]
        }
      }
    }
  });
});

API reference: https://api.highcharts.com/highstock/plotOptions.series.dataGrouping

Docs reference: https://www.highcharts.com/docs/advanced-chart-features/data-grouping