JSFiddle - React, Tailwind, and code Playground

HTML

<div id="bart"></div>

JavaScript

//Goal: do most of the logic in a single line using just the OR
//operator and a ternary

// bar, either undefined or a cached selection of $('#bar')
var bar = $('#bar');

// if bar isn't undefined/falsey, use bar, otherwise query the
// DOM for the div 'bar' so we can cache it in 'foo' if
// bar has a length greater than 1

// if bar doesn't exist in the global scope and isn't currently
// in the DOM, we'll dynamically create a div and set it's ID to
// 'bar' instead.

var foo = bar = bar && bar.length && bar ||
    (bar = $('#bar')).length ? bar :
    $('<div />', { id: 'bar' });

console.log(foo, bar);