echarts图例点击事件

//图例切换事件

var legend；
    var triggerAction = function(action, selected) {
        legend = [];
        for (name in selected) {
            if (selected.hasOwnProperty(name)) {
                legend.push({
                    name: name
                });
            }
        }
        myCharts.dispatchAction({
            type: action,
            batch: legend
        });
    };
    //是否只选择一个图例
    var isFirstUnSelect = function(selected) {
        var unSelectedCount = 0;
        for (name in selected) {
            if (!selected.hasOwnProperty(name)) {
                continue;
            }
            if (selected[name] == false) {
                unSelectedCount++;
            }
        }
        return unSelectedCount == 1;
    };
    //定义一个开关，第一次点击的时候才翻转。当所有都被选择的时候，再次点击不会只显示一个。
    var onOff = true;
    myCharts.on('legendselectchanged', function(obj) {
        var selected = obj.selected;
        var legend = obj.name;
        // 使用 legendToggleSelect Action 会重新触发 legendselectchanged Event，导致本函数重复运行
        // 使得 无 selected 对象
        if (selected != undefined && isFirstUnSelect(selected) && onOff) {
            triggerAction('legendToggleSelect', selected);
            onOff = false;
        }
    });
},