Callback option not working

[webroru]

I try use the callback option as described here: http://www.highcharts.com/docs/export-module/render-charts-serverside. But its seems this options work another at your package.

My code:

//Include the exporter module
const exporter = require('highcharts-export-server');

//Export settings
var exportSettings = {
  type: 'pdf',
  instr: {
    title: {
      text: 'My Chart'
    },
    xAxis: {
      categories: ["Jan", "Feb", "Mar", "Apr", "Mar", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
    },
    series: [
      {
        type: 'line',
        data: [1, 3, 2, 4]
      },
      {
        type: 'line',
        data: [5, 3, 4, 2]
      }
    ]
  },
  callback: function (chart) { chart.renderer.arc(200, 150, 100, 50, -Math.PI, 0).attr({ fill: '#FCFFC5', stroke: 'black', 'stroke-width': 1 }).add(); },
  outfile: 'test.pdf',
};

//Set up a pool of PhantomJS workers
exporter.initPool();

/*
 Export settings corresponds to the available CLI arguments described
 above.
 */
exporter.export(exportSettings, function (err, res) {
  exporter.killPool();
});

[cvasseng]

Hi webroru, the callback needs to be a string.

A future enhancement may remove this requirement when using the export server as a node module.