highcharts-export-server yAxis formatter does not work - highcharts

Question

highcharts can set yAxis formatter function to change yAxis format,but
using highcharts-export-server to generate image, yAxis formatter does not work.
the demo code is like this:
const exporter = require("highcharts-export-server");
const fs = require("fs");
const options = {
"xAxis": {
"categories": ['1', '2', '3', '4']
},
"yAxis": {
title: {
text: 'times'
},
plotLines: [
{
value: 0,
width: 1,
color: "#808080"
}
],
labels: {
enabled: true,
formatter: function () {
return this.value * 100
},
},
},
"series": [{
"data": [1, 3, 2, 4],
"type": "line"
}, {
"data": [5, 3, 4, 2],
"type": "line"
}]
}
const exportSettings = {type: 'png',options}
//Set up a pool of PhantomJS workers
exporter.initPool();
//Perform an export
exporter.export(exportSettings, function (err, res) {
var dataBuffer = new Buffer(res.data, 'base64');
fs.writeFile("out.png", dataBuffer, function (err) {
if (err) {
console.log(err);
} else {
console.log("save success！");
}
});
exporter.killPool();
});
any one have some suggestions?thanks!
the result:
demo result

Answer 1

There's a bug associated with this problem: https://github.com/highcharts/node-export-server/issues/70
However you can use the formatter function in callback export parameter like this:
{
"type": "Png",
callback: `function(chart) {
chart.yAxis[0].update({
labels: {
enabled: true,
formatter: function() {
return this.value * 100
}
}
});
}`,
options: {
"xAxis": {
"categories": ['1', '2', '3', '4', '5']
(...)
Notice that the whole function is a String.