[Solved]-Add series / data to highchart gantt from function-Highcharts

I prepared a demo which should help you to implement data adding functionality to your project.

chart.addSeries({
    data: [{
      start: today + day * Math.floor(Math.random() + i),
      end: today + day * Math.floor(Math.random() + i * 2),
      name: 'test' + i,
    }]
});

Demo: https://jsfiddle.net/BlackLabel/ue2xg6o7/1/

API: https://api.highcharts.com/class-reference/Highcharts.Chart#addSeries

Let me know if you have any further questions.