JSFiddle - React, Tailwind, and code Playground

JavaScript

var foo;

var myString1 = String(foo); // "undefined" as a string
console.log(myString1);

var myString2 = foo + ''; // "undefined" as a string
console.log(myString2);

var myString3 = foo.toString(); // throws an exception
console.log(myString3);