export declare function is(val: unknown, type: string): boolean;
export declare function isString(val: unknown): val is string;
export declare function isFunction(val: unknown): val is Function;
export declare function isBoolean(val: unknown): val is boolean;
export declare const canUseDOM: boolean;
export declare const inBrowser: boolean;
export declare const UA: string | boolean;
export declare const isWeChat: boolean;