时间戳字符串 比如 1639025996224，声明为字符串类型，判断length > 0 返回false，为什么

serverData = JSON.parse(result, (key:string, value: string | Number | Object): Object| string| Number => { 
  if (key == ‘pubdate’ && typeof value == ‘number’) { 
    value = value.toString() 
  } 
  return value 
})
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