ohos.util.json转换string问题

stringify(value: Object, replacer?: (number | string)[] | null, space?: string | number): string 
stringify(value: Object, replacer?: Transformer, space?: string | number): string 
//replacer用于替换对象的键值对。它是一个函数，接收两个参数：键和值，然后返回一个新的键值对 
//space用于在生成的字符串中插入空格。它是一个字符串或数字，代表插入空格的数量

interface Person { 
  name: string; 
  age: number; 
  city: string; 
} 
let obj = {"name": "John", "age": 30, "city": "ChongQing"} as Person; 
let str = JSON.stringify(obj); 
 
 
//操作特定对象属性的转换 
type Transformer = (this: Object, key: string, value: Object) => Object | undefined | null; 
interface Person { 
  name: string; 
  age: number; 
  city: string; 
} 
let obj = {"name": "John", "age": 30, "city": "ChongQing"} as Person; 
//replacer用于在序列化过程中处理特定的对象属性 
//接受一个键和一个值作为参数。如果键是 ‘age’，则返回 undefined；否则，返回值本身 
let replacer: Transformer = (key, value) => { 
  if (key === 'age') { 
    return undefined; 
  } 
  return value; 
}; 
let jsonString = JSON.stringify(obj, replacer, 2); 
console.log(jsonString);