javascript - 如何获取 JSON 数组中的 JSON 对象名称

Question

我需要获取值“channelA”和“channelB”，它们是对象名称。

JSON 文件:

[
    {
        "channelA": {
            "programmes": [
                {
                    "start_utc": 1522208700,
                    "stop_utc": 1522209600,
                },
                {
                    "start_utc": 1522209600,
                    "stop_utc": 1522210800,
                }
            ]    
        }
   },
   {
      "channelB": {
          "programmes": [
               {
                  "start_utc": 1522256700,
                  "stop_utc": 1522260800                     
               },
               {
                  "start_utc": 152229000,
                  "stop_utc": 1522318900,                     
               }
           ]
       }
   }
]    

我将 JSON 存储在名为 epg 的值中，并使用以下命令迭代 epg:

for (var k = 0; k < epg.length; k++) {          
    console.log(_epg[k]);   
}

我需要将对象的名称与另一个变量(channelId)进行比较:

for (var k = 0; k < _epg.length; k++) {
    if (channelId == epg[k]) {
       console.log(_epg[k]);
    }
}

Answer 1

为此使用 Object.keys() 方法:

let myArr = [
    {
        "channelA": {
            "programmes": [
                {
                    "start_utc": 1522208700,
                    "stop_utc": 1522209600,
                },
                {
                    "start_utc": 1522209600,
                    "stop_utc": 1522210800,
                }
            ]    
        }
   },
   {
      "channelB": {
          "programmes": [
              {
                  "start_utc": 1522256700,
                  "stop_utc": 1522260800                     
              },
              {
                  "start_utc": 152229000,
                  "stop_utc": 1522318900,                     
               }
           ]
       }
   }
]    

for (let item of myArr) {
  for (let key of Object.keys(item)) {
    if (key == "channelA" || key == "channelB") console.log(key + ": ", item[key])
  }
}

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys