javascript - 如何使用 JavaScript 将默认值添加到 JSON？

Question

{
    "Les Miserables":{
        "lang": "French",
        "type": "Movie"
    },
    "Some German Book":{
        "lang": "German",
        "type": "Book"
    },
    "Gangnam Style":{
        "lang": "Korean",
        "type": "Song"
    },
    "Captain America":{
         "type": "Comic Book"
    },
    "Some song":{
         "type": "Song"
    }
}

我希望所有没有语言的对象默认设置为英语。

如何通过 JavaScript 执行此操作？我想更新原始 JSON 对象，而不是创建新对象。

示例输出:

{
    "Les Miserables":{
        "lang": "French",
        "type": "Movie"
    },
    "Some German Book":{
        "lang": "German",
        "type": "Book"
    },
    "Gangnam Style":{
        "lang": "Korean",
        "type": "Song"
    },
    "Captain America":{
         "type": "Comic Book",
         "lang": "English"
    },
    "Some song":{
         "type": "Song",
         "lang": "English"
    }
}

提前致谢!

Answer 1

您可以使用 Object.keys 迭代对象键，然后将所需的属性设置为默认值(如果该属性不存在):

var obj = {
  "Les Miserables": {
    "lang": "French",
    "type": "Movie"
  },
  "Some German Book": {
    "lang": "German",
    "type": "Book"
  },
  "Gangnam Style": {
    "lang": "Korean",
    "type": "Song"
  },
  "Captain America": {
    "type": "Comic Book"
  },
  "Some song": {
    "type": "Song"
  }
};

// for each key of the object...
for (let key of Object.keys(obj)) {
  // set the "lang" property to "English" if it does not exist
  if (obj[key].lang == null) {
    obj[key].lang = "English";
  }

  // set more default values the same way if you want
}

console.log(obj);