export declare const objOmit: <T extends object, K extends keyof T>(obj: T | null | undefined, fields: K[]) => Omit<T, K>;
export declare const objPick: <T extends object, K extends keyof T>(obj: T | null | undefined, fields: K[]) => Pick<T, K>;
export declare const objOmitUndefined: <T extends object>(obj: T) => object;
export declare const isObject: (obj: any) => boolean;
/**
 * 合并覆盖对象属性值，如果第一层值为对象也进行合并
 *
 * e.g.
 * mergeObjectRoot({ a:1 }, { a:2, b:{c:3} })                    => { a:2, b:{c:3} }
 * mergeObjectRoot({ a:1, b:{d:4} }, { a:2, b:{c:3} })           => { a:2, b:{d:4, c:3} } // 对象会合并
 * mergeObjectRoot({ a:1, b:{d:{x:1}} }, { a:2, b:{d:{y:2}} })   => { a:2, b:{d:{y:2}} }  // 深层级的属性值只会覆盖
 * mergeObjectRoot({ a:1, b:[1] }, { a:2, b:[2] })               => { a:2, b:[2] }        // 数组不会合并
 * mergeObjectRoot({ a:1 }, { a:undefined })                     => { a:1 }               // undefined 默认跳过不覆盖
 * mergeObjectRoot({ a:1 }, { a:undefined }, false)              => { a:undefined }       // undefined 可以选择覆盖
 */
export declare const mergeObjectRoot: <T extends object, U extends object>(obj: T | null | undefined, update: U | null | undefined, skipUndefined?: boolean) => Omit<T, keyof U> & U;