d3.js nvd3 issue: display the dollar sign, and the currency format in the tooltip

I´m using this function

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

In order to attach the dollar sign, and the currency format, to one of my y-axis.

Is it possible to display the dollar sign, and the currency format in the tooltip also?

This is my graph: http://codepen.io/neonpulp/pen/zBZgrv . Below is the code also.

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();

http://codepen.io/meetamit/pen/AXRBmG

1) Make the tick format into a named function, so that you can reuse it:

var dollarFormat = function(d) { return '$' + d3.format(',f')(d) };

2) Use it for the ticks like this

chart.yAxis2.tickFormat(dollarFormat)

3) Use it in the tooltip like this:

dollarFormat(key.series[0].value)