A better checking for type of a value in javascript

typeOf.js

const capitalise = word =>
  word[0].toUpperCase() + word.slice(1).toLowerCase()

/** (val: any) -> string */
const typeOf = val => {
  if (val === null)                        return 'null'
  if (val === void val)                    return 'undefined'
  if (Number.isNaN(val))                   return 'NaN'
  if (Array.isArray(val))                  return 'Array'
  if (RegExp.prototype.isPrototypeOf(val)) return 'RegExp'
  
  return capitalise(typeof val)
}


/**
 * Example
 */
console.log( typeof undefined  )  // -> 'undefined'
console.log( typeof null       )  // -> 'object' :(
console.log( typeof NaN        )  // -> 'number' :(
console.log( typeof 1          )  // -> 'number'
console.log( typeof 'abc'      )  // -> 'string'
console.log( typeof true       )  // -> 'boolean'
console.log( typeof Symbol(0)  )  // -> 'symbol'
console.log( typeof {}         )  // -> 'object'
console.log( typeof []         )  // -> 'object' :(
console.log( typeof /abc/g     )  // -> 'object' :(

console.log( typeOf(undefined) )  // -> 'undefined'
console.log( typeOf(null)      )  // -> 'null'   :)
console.log( typeOf(NaN)       )  // -> 'NaN'    :)
console.log( typeOf(1)         )  // -> 'Number'
console.log( typeOf('abc')     )  // -> 'String'
console.log( typeOf(true)      )  // -> 'Boolean'
console.log( typeOf(Symbol(0)) )  // -> 'Symbol'
console.log( typeOf({})        )  // -> 'Object'
console.log( typeOf([])        )  // -> 'Array'  :)
console.log( typeOf(/abc/g)    )  // -> 'RegExp' :)