how to use callback function for tooltop.formatter?

At javascript:

tooltip: {
    formatter: function () {
        return new Date(this.x).toLocaleString() + '<br><b>内存：</b>' + byte_to_string(this.y)
    }
}

But typescript this is a class.

[cebor]

The options object gets extracted from the Charts object, so it should work as you described.

new Chart({
...
tooltip: {
  formatter: function () {
     return new Date(this.x).toLocaleString() + '<br><b>内存：</b>' + byte_to_string(this.y)
  }
}
...
});

Docs: http://www.highcharts.com/docs/chart-concepts/tooltip

[vapao]

yes, is solved. thanks.