JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.8/d3.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/c3/0.4.10/c3.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/c3/0.4.10/c3.js"></script>
<div id="left"></div>

JavaScript

function checkIt(data) {
    var countriesByName = d3.nest()
        .key(function (d) {
        return d.Country_Names;
    })
        .entries(data);
    //console.log(countriesByName)
    var data = JSON.stringify(countriesByName)
    var data = JSON.parse(data);
   
        function makePie() {
            function myfunc(data) {
                var obj = [];
// <<<<<<<<<<<<<<<<<<<<<<<<<<<<
                for (var i in data) {
                    obj.push(data[i].key+': [Road: '+ 
                             data[i].values[0].Road+ ", Rails: "
                             +data[i].values[0].Rail+"]<br>");
                }
                document.getElementById("left").innerHTML=obj.toString();
            }
            var data1 = myfunc(data)
            //console.log(data)
        }
    makePie();
};



d3.json("https://gist.githubusercontent.com/heenaI/cbbc5c5f49994f174376/raw/82cd19eff7db367193cf8ce00144a40ea8d140ac/data.json", checkIt);