javascript - 当尝试使用forEach函数控制台记录简单对象时，我变得无法定义(I'm getting undefined when trying to console log a simple object using a forEach function)

Question

I know this is a noobie question, but I just can't figure out why I'm gettgin undefined when I try to console log the property of an object from my database when I'm using the following forEach function.

(我知道这是一个noobie问题，但是当我使用以下forEach函数尝试从数据库中控制台记录对象的属性时，我只是想不出为什么我未定义gettgin的原因。)

  readLocations = () => {
    console.log("readlocations called")
    let locations = 
    firebase
    .database()
    .ref("/locations/");
    locations.on('value', (snapshot) => {
      snapshot.forEach((thing) => {
        console.log("thingy object", thing)
        console.log("thingy latitude", thing.latitude)
      })
    });  
  }

The first console.log logs the following

(第一个console.log记录以下内容)

thingy Object {
  "created_at": 1574980834124,
  "latitude": 52.4673777,
  "longitude": 13.4327486,
}
thingy Object {
  "created_at": 1575026634915,
  "latitude": 52.5169399,
  "longitude": 13.4175105,
}
thingy Object {
  "created_at": 1575043262077,
  "latitude": 52.5177105,
  "longitude": 13.4153796,
}
thingy Object {
  "created_at": 1575115938922,
  "latitude": 52.5097333,
  "longitude": 13.2829992,
}

However, the second log returns undefined

(但是，第二个日志返回未定义)

thingy latitude undefined
thingy latitude undefined
thingy latitude undefined
thingy latitude undefined
thingy latitude undefined

What am I missing here?

(我在这里想念什么？)

  ask by Yahir Casas translate from so

Answer 1

等待大神答复