JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://d3js.org/d3.v2.js"></script>

JavaScript

var localData;

console.log("first");
console.log(localData);

function doSomething() {
    console.log("second");
    console.log(localData);
}

d3.json("/echo/json", function(jsonData) {
   localData = jsonData;
   doSomething();
});