import { MessageFunctionType, Result } from '../types';
export interface IsJSONErrors {
    TARGET_ARGUMENT_NOT_A_STRING: MessageFunctionType;
}
export declare const IS_JSON_ERRORS: IsJSONErrors;
/**
 * Tests whether the `target` string is valid JSON
 *
 * ### Example
 * ```
 * expect(isJSON('{ "key": "value" }').value).toBeTruthy()
 * ```
 * @param target The target string
 */
export declare function isJSON(target: string, options: any): Result<boolean | undefined>;