问dygraphs禁用两个系列的图例

EN

g = new Dygraph(
    document.getElementById("graph"),
    "X,Y,min,max\n" +
    "1,6,3,12\n" +
    "2,3,3,12\n" +
    "3,4,3,12\n" +
    "4,6,3,12\n" +
    "5,8,3,12\n" +
    "6,10,3,12\n" +
    "7,12,3,12\n" +
    "8,10,3,12\n",
    {
      legend: 'always',
      series: {
        min: { color: 'red' },
        max: { color: 'red' },
      },
      legendFormatter: function(data) {
        data.series = [data.series[0]];  // pick whichever series you want to keep
        return Dygraph.Plugins.Legend.defaultFormatter.call(this, data);
      }
    });

LegendFormatter(data) {
if (data.x == null) {
  // This happens when there's no selection and {legend: 'always'} is set.
  return data.series.map(function(series) { 
if(series.labelHTML != 'counter_label')
return series.dashHTML + ' ' + series.labelHTML }).join(' ');
}
var html = data.xHTML;
return html;
}

this.graph = new Dygraph(document.getElementById("graph_div"), 
    this.data,
    {
      legend: 'always',
      drawPoints: true,
      animatedZooms: true,
      showRoller: true,
      rollPeriod: 14,
      legendFormatter: this.LegendFormatter,
    });