[Solved]-Highcharts: Get visibility of series after legendItemClick-Highcharts

You can get this behavior a little modyfing your function:

plotOptions: {
  series: {
    events: {
      legendItemClick: function(event) {
          var series = this.yAxis.series,
              seriesLen = series.length,
              visible = this.visible ? 1 : -1; 
              // +1 when visible series, because it will be changed after that callback

          for(var i = 0; i < seriesLen; i++) {
            if(!series[i].visible) {
              visible++;
            }
          }
          if(visible >= 2){
            //do some action
          }
      }
    }
  }
},