const toString = Object.prototype.toString;
export function is(val: unknown, type: string) {
  return toString.call(val) === `[object ${type}]`;
export function isDef<T = unknown>(val?: T): val is T {
  return typeof val !== 'undefined';
export function isUnDef<T = unknown>(val?: T): val is T {
  return !isDef(val);
export function isObject(val: any): val is Record<any, any> {
  return val !== null && is(val, 'Object');
export function isEmpty<T = unknown>(val: T): val is T {
  if (isArray(val) || isString(val)) {
    return val.length === 0;
  if (val instanceof Map || val instanceof Set) {
    return val.size === 0;
  if (isObject(val)) {
    return Object.keys(val).length === 0;
  return false;
export function isDate(val: unknown): val is Date {
  return is(val, 'Date');
export function isNull(val: unknown): val is null {
  return val === null;
// 是否是 null
export function isnull(val:unknown):val is null {
  return is(val,'Null')
export function isNullAndUnDef(val: unknown): val is null | undefined {
  return isUnDef(val) && isNull(val);
export function isNullOrUnDef(val: unknown): val is null | undefined {
  return isUnDef(val) || isNull(val);
export function isNumber(val: unknown): val is number {
  return is(val, 'Number');
export function isPromise<T = any>(val: unknown): val is Promise<T> {
  return is(val, 'Promise') && isObject(val) && isFunction(val.then) && isFunction(val.catch);
export function isString(val: unknown): val is string {
  return is(val, 'String');
export function isFunction(val: unknown): val is Function {
  return typeof val === 'function';
export function isBoolean(val: unknown): val is boolean {
  return is(val, 'Boolean');
export function isRegExp(val: unknown): val is RegExp {
  return is(val, 'RegExp');
export function isArray(val: any): val is Array<any> {
  return val && Array.isArray(val);
export function isWindow(val: any): val is Window {
  return typeof window !== 'undefined' && is(val, 'Window');
export function isElement(val: unknown): val is Element {
  return isObject(val) && !!val.tagName;
export function isMap(val: unknown): val is Map<any, any> {
  return is(val, 'Map');
export const isServer = typeof window === 'undefined';
export const isClient = !isServer;
export function isUrl(path: string): boolean {
  const reg =
    /(((^https?:(?:\/\/)?)(?:[-;:&=\+\$,\w]+@)?[A-Za-z0-9.-]+(?::\d+)?|(?:www.|[-;:&=\+\$,\w]+@)[A-Za-z0-9.-]+)((?:\/[\+~%\/.\w-_]*)?\??(?:[-\+=&;%@.\w_]*)#?(?:[\w]*))?)$/;
  return reg.test(path);
				
const toString = Object.prototype.toString;
export function is(val: unknown, type: string) {
  return toString.call(val) === `[object ${type}]`;
export function isDef<T = unknown>(val?: T): val is T {
  return typeof val !== 'undefined';
expor
				Vue带默认参数报错 PointerEvent {isTrusted: true, pointerId: 1, width: 1, height: 1, pressure: 0, …}
                报错：类型“AsyncThunkAction＜unknown, void, AsyncThunkConfig＞”的参数不能赋给类型“AnyAction”的参数，
                    qq_37915328: 
                    我也遇到这个问题了，感谢提供解决的方法。
                JavaScript浮点数加法计算，防止精度丢失方法
                    阿里嘎吧创始人: 
                    小白一枚，你学完肯定比我更强的
                JavaScript浮点数加法计算，防止精度丢失方法
                    普通网友: 
                    这学期要学JavaScript，感觉博主技术很厉害，可以加您微信随时交流技术吗