JSFiddle - React, Tailwind, and code Playground

HTML

<div id="chartContainDiv">&nbsp;</div>

JavaScript

function setChart(chartContainer) {
    var variableName = new String(chartContainer);
    return variableName.toUpperCase();
};

var chart = setChart("chartContainDiv");
var chart2 = setChart("blahBlah");
console.log(chart.toString());
console.log(chart2.toString());