Custom Highcharts Context Menu Button Appearing in Every Chart on Page

Question

I have a page with several charts, and I need to be able to add specific options to the exporting context menu for each chart. This is the code I am using:

Answer 1

Starting from Paweł Fus answer, I found out a cleaner solution for the general case. The main issue is you need not to mess around with original object and extend it. Instead, you'd be better cloning it. Please note that my solution requires jQuery.

function appendExportButton(mytext, myfunction){
  var defaultButtons = Highcharts.getOptions().exporting.buttons; // get default Highchart Export buttons
  var myButtons = $.extend(true, {}, defaultButtons);
  myButtons.contextButton.menuItems.push({
    text: mytext,
    onclick: myfunction
  });
  return {buttons: myButtons};
}

To insert this button in the desired chart, define the chart this way:

var mychart = new Highcharts.Chart({
  chart: {
    ...whatever...
  },
  plotOptions: {
    ...whatever...
  },
  series: {
    ...whatever...
  },
  exporting: appendExportButton("Save data in CSV format", saveCSV)
});

In the case of OP problem, this is the line you have to use:

exporting: appendExportButton("Tokyo Only Option", HelloWorld)

JSFiddle