Nodejs Utililty Methods Object Type Check

Object.prototype.isBoolean = function () {
    return (typeof (this.valueOf()) === 'boolean')
};

Object.prototype.isInteger = function () {
    var number = parseFloat(this.valueOf());
    return number.isNumber() && /^-?\d+$/.test(String(number));
};

Object.prototype.isJSON = function () {
    try {
        JSON.parse(this);
        return true;
    } catch (e) {
        return false;

Object.prototype.isTypeOf = function(type) {
  var that = this;
  return Object.prototype.toString.call(that) === '[object ' + type + ']';

Object.defineProperty(Object.prototype, 'type', {
    get() {
        let value
        if(this.val) {
          value = this.val
        else {
          value = this.valueOf()
        let is_arr  = value instanceof Array || Array.isArray(value)
        let is_num  = value instanceof Number || !isNaN(value) 
        let is_bool = value instanceof Boolean || typeof value == 'boolean'
        let is_str  = value instanceof String || typeof value == 'string'
        let is_fn   = value instanceof Function || typeof value == 'function'
        let is_rx   = value instanceof RegExp
        let is_obj  = typeof value == 'object'
        if(is_str) {
          return 'string'
        if(is_bool) {
          return 'boolean'
        if(is_num) {
          return 'number'
        if(is_rx) {
          return 'regex'
        if(is_arr) {
            return 'array'
        if(is_fn) {
          return 'function'
        if(is_obj) {
          return 'object'
})