const opt = Object.prototype.toString;

export function isArray(obj: any): obj is any[] {
  return opt.call(obj) === '[object Array]';
}

export function isObject(obj: any): obj is { [key: string]: any } {
  return opt.call(obj) === '[object Object]';
}

export function isString(obj: any): obj is string {
  return opt.call(obj) === '[object String]';
}

export function isNumber(obj: any): obj is number {
  return opt.call(obj) === '[object Number]' && obj === obj;
}

export function isRegExp(obj: any) {
  return opt.call(obj) === '[object RegExp]';
}

export function isObjectEmpty(obj: any) {
  for (let _key in obj) {
    return false;
  }
  return true;
}