how to use callback function for tooltop.formatter?

[vapao]

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]

@cebor thanks
byte_to_string is a function convert Byte to KB MB or GB, like this:

private byteToString(data: any): string {
        let kb = data / 1024
        if (kb > 1024) {
            let mb = kb / 1024
            if (mb > 1024) {
                return (mb / 1024).toFixed(2) + ' GB'
            } else {
                return mb.toFixed(2) + ' MB'
            }
        }
        return kb.toFixed(2) + ' KB'
    }

now browser console print: Uncaught TypeError: this.byteToString is not a function

[cebor]

I think the Problem is that, the options object and the class where you creating the Chart have different contexts.

Maybe making byteToString to a static method will solve this. - Example

Or use something like: var _this = this.

For further help, please show me more code of the class you declaring your chart.

[cebor]

I think, the problem is solved, so i'm closing this. Feel free to reopen.

[vapao]

yes, is solved. thanks.