5-undefined-null-NaN.js

'use strict';

// undefined
let emptyScalar;
console.log({ emptyScalar }, typeof emptyScalar);

// null
const emptyObject = null;
console.log({ emptyObject }, typeof emptyObject);

// NaN
let count = NaN;
console.log({ count }, typeof count);

count = undefined + 1;
console.dir({ count });

console.log(Infinity, -Infinity, typeof Infinity);

const s = (
  emptyObject === null ?
    'emptyObject is null' :
    'emptyObject is not null'
);
console.log(s);