isObject to test if a variable is actually only an Object

isObject.js

const isObject = v => Object.prototype.toString.call(v) === '[object Object]'

Object.entries({
'{}': {},
 Set: new Set([1,2,3,4]),
 Date: new Date(),
 null: null,
 undefined: undefined,
 string: 'string',
 NaN: NaN,
 func: () => {},
 Function: Function,
 '3': 3,
}).reduce((acc, [k, v]) => {
  acc[k] = isObject(v)
  return acc
}, {})