any-serialize/src/type.ts

Serialize / Deserialize any JavaScript objects, as long as you provides how-to. I have already provided `Date`, `RegExp`, `Set` and `Function`.

export type TypeNativeSerializable = 'string' | 'number' | 'boolean'
export type TypeNativeNonSerializable = 'bigint' | 'symbol' | 'undefined' | 'function' | 'object'
export type TypeExtra = 'Null' | 'Array' | 'Named' | 'Constructor' | 'NaN' | 'Infinity'
export type TypeAll = TypeNativeSerializable | TypeNativeNonSerializable | TypeExtra

export function getTypeofDetailed (a: any) {
  const typeof_ = typeof a
  const output: {
    typeof_: TypeNativeSerializable | TypeNativeNonSerializable
    is: TypeAll[]
    id?: Function
    description?: string
    entry: any
  } = {
    typeof_,
    is: [],
    entry: a
  }

  if (typeof_ === 'object') {
    if (!a) {
      output.is = ['Null']
    } else {
      /**
       * constructor will return Class constructor
       * or Object constructor for an Object
       *
       * The actual constructor name can be accessed via
       * `constructor.name`
       *
       * constructor can checked for equality as well, for example
       * Object === Object
       *
       * Not sure what happens when you `extends` Object or Array
       * in which case, it might be better to check `constructor.name`
       */
      output.id = a.constructor
      if (output.id === Object) {
        output.is = ['object']
      } else if (output.id === Array) {
        output.is = ['Array']
        /**
         * Array.isArray() also includes classes that extend Array
         * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray
         *
         * Given a TypedArray instance, false is always returned
         */
      // } else if (Array.isArray(a)) {
      //   output.is = ['NamedArray']
      } else {
        output.is = ['Named']
      }
    }
  } else if (typeof_ === 'function') {
    /**
     * Checking for Class constructor is a difficult topic.
     * https://stackoverflow.com/questions/40922531/how-to-check-if-a-javascript-function-is-a-constructor
     *
     * Probably the safest way is by checking prototype.
     *
     * new a() is more failsafe, but is dangerous. (because you ran a function)
     */
    if (!a.prototype) {
      /**
       * Arrow function doesn't have a prototype
       */
      output.is = ['function']
    } else {
      output.id = a.prototype.constructor

      if (Object.getOwnPropertyNames(a.prototype).some((el) => el !== 'constructor')) {
        output.description = 'Can also be a class constructor in some cases'
        if (/[A-Z]/.test(a.prototype.constructor.name[0])) {
          output.is = ['Constructor', 'function']
        } else {
          output.is = ['function', 'Constructor']
        }
      } else {
        output.is = ['Constructor']
      }
    }
  } else if (typeof_ === 'number') {
    if (isNaN(a)) {
      output.is = ['NaN'] // JSON.stringify returns null
    } else if (!isFinite(a)) {
      output.is = ['Infinity'] // JSON.stringify returns null
    } else if (Math.round(a) === a) {
      output.description = 'Integer' // JSON.stringify cannot distinguish, nor do JavaScript
    }
  }

  if (output.is.length === 0) {
    output.is = [typeof_]
  }

  return output
}

export function isArray (a: any, t?: ReturnType<typeof getTypeofDetailed>): a is any[] {
  return (t || getTypeofDetailed(a)).is[0] === 'Array'
}

export function isObject (a: any, t?: ReturnType<typeof getTypeofDetailed>): a is Record<string, any> {
  return (t || getTypeofDetailed(a).is[0]) === 'object'
}