D3.js is the most popular library for creating interactive charts in any web application. You can also use D3.js library in Lightning components for graphical representation of data. These charts can be used to give sales insights to a member ( Salesforce user) of the sales team.  This article will show how can we leverage D3.js to build charts with a simple example.

First, let’s see the component code.

D3Charts.cmp

D3ChartsController.js

({
    initD3Charts : function(component, event, helper) {

        var width = 960;
        var height = 500;

        // Create SVG element, we can't just use  tag in lightning component
        // So creating one dynamically using jquery
        var svg = d3.select("body")
        .append("svg")
        .attr("width", width)
        .attr("height", height);	

        // Calling server-action to get the data
        var action = component.get("c.getData");

        // Create a callback that is executed after
        // the server-side action returns
        action.setCallback(this, function(response) {
            var state = response.getState();
            if (state === "SUCCESS") {
                let data = response.getReturnValue();
                console.log(data);
                // Render the returned data as a pie chart
                helper.renderChart( component, data );
            }
            else if(state === "ERROR") {
                var errors = response.getError();
                if (errors) {
                    if (errors[0] && errors[0].message) {
                        console.log("Error message: " +
                                    errors[0].message);
                    }
                } else {
                    console.log("Unknown error");
                }
            }
        });

        $A.enqueueAction(action);

    }
})

D3ChartsHelper.js

({
    renderChart : function( component, data ) {
        var svg = d3.select("svg"),
            width = +svg.attr("width"),
            height = +svg.attr("height"),
            radius = Math.min(width, height) / 2,
            g = svg.append("g").attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");

        var color = d3.scaleOrdinal(["#98abc5", "#8a89a6", "#7b6888", "#6b486b", "#a05d56", "#d0743c", "#ff8c00"]);

        var pie = d3.pie()
        .sort(null)
        .value(function(d) { return d.candidates; });

        var path = d3.arc()
        .outerRadius(radius - 10)
        .innerRadius(0);

        var label = d3.arc()
        .outerRadius(radius - 80)
        .innerRadius(radius - 80);

        var arc = g.selectAll(".arc")
        .data(pie(data))
        .enter().append("g")
        .attr("class", "arc");

        arc.append("path")
        .attr("d", path)
        .attr("fill", function(d) { return color(d.data.age); });

        arc.append("text")
        .attr("transform", function(d) { return "translate(" + label.centroid(d) + ")"; })
        .attr("dy", "0.35em")
        .text(function(d) { return d.data.age; });
    }
})

So, we have included d3.js library along with jquery.js and then called a server-side action when the script has loaded in order to fetch the chart data. In the defined callback function we passed that data to a helper function which rendered the chart.

D3ChartsController.apex

public class D3ChartsController {
  
    @AuraEnabled
    public static List getData(){
      
        // For this example, it's just a static data but it can be generated 
        // as per any business logic
        List lstData = new List();
        lstData.add( new PieChart( '=65', 61 ) );
        return lstData;
    }
    
    public class PieChart {
        @AuraEnabled public String age;
        @AuraEnabled public Integer candidates;
        
        public PieChart( String age, Integer candidates ) {
            this.age = age;
            this.candidates = candidates;
        }
    }
}

Reference to resources –

• D3.js Library
• Jquery Library