更改d3.js（nvd3）自定义工具提示

Question

我正在关注本教程https://bytutorial.com/blogs/open-source-chart/learn-how-to-create-multiple-bar-charts-with-multiple-line-charts-in-nvd3，这很棒。

尽管如此，它还是以炫目的方式显示键值。而不是键的名称，显示一个div与键的背景颜色：

<div class='tooltip'>
  <span>Legend:</span> 
  <div style='background:" + key.series[0].color + ";display:inline-block;height:150px;width:150px;'>&#160;</div>
</div>

如何显示密钥的名称？而不是其颜色。

这是我的图表：http://codepen.io/neonpulp/pen/zBZgrv。以下是完整的代码。

function buildGraph(){
    //this will hold of our main data consists of multiple chart data
    var data = [];

    //variables to hold monthly month
    var monthList = ['Ene 2016','Feb 2016','Mar 2016','Apr 2016','May 2014','Jun 2016','Jul 2016','Aug 2016', 'Sep 2016', 'Oct 2016', 'Nov 2016', 'Dec 2016'];
    var monthlyIncome = [0, 2757820, 3447270, 0, 0, 0, 0, 0, 0, 0, 0, 0];
    var companiesNumber = [0, 4, 5, 0, 0, 0, 0, 0, 0, 0, 0, 0];

    //Array to hold each individual coordinate x and y values
    var monthlyIncomeValues = [];
    var companiesNumberValues = [];

    //Looping the data and fetch into array
    for(var i = 0; i < monthList.length; i++){
        var xyIncome = {x: i, y: monthlyIncome[i]};
        monthlyIncomeValues.push(xyIncome);

        var xyCompanies = {x: i, y: companiesNumber[i]};
        companiesNumberValues.push(xyCompanies);

    }

    //bar chart
    var dataIncome = { key: "Monthly Income", values: monthlyIncomeValues, type: "bar", yAxis: 2, color: '#00913B' }

    //line chart
    var dataCompanies = { key: "Amount of companies", values: companiesNumberValues, type: "line", yAxis: 1, color: '#00C3D9' }

    //Insert the values array into data variable
    data.push(dataIncome);
    data.push(dataCompanies);

    //build the graph
    nv.addGraph(function () {
        //build as multichart graphs and set the margin right and left to 100px.
        var chart = nv.models.multiChart()
                    .margin({left: 100, right: 100})

        //customize the tool tip
        chart.tooltip.contentGenerator(function (key, x, y, e, graph) {
            return "<div class='tooltip'><span>Month:</span> " + monthList[key.index] + "</div>" + "<div class='tooltip'><span>Value:</span> " + key.series[0].value + "</div><div class='tooltip'><span>Legend:</span> <div style='background:" + key.series[0].color + ";display:inline-block;height:15px;width:15px;'>&#160;</div></div>";
        });

        //Overwrite the x axis label and replace it with the month name
        chart.xAxis.tickFormat(function (d) { return monthList[d] });

        //Chart Interpolate
        chart.interpolate("linear")

        //Dollar Sign
        chart.yAxis2.tickFormat(function(d) { return '$' + d3.format(',f')(d) });

        //get the chart svg object and fecth the data to build the chart
        d3.select('#chart svg')
            .datum(data)
            .transition().duration(500).call(chart);
        return chart;
    });
}

//call the function to build the graph.
buildGraph();