<!DOCTYPE html>
<html lang="zh">
    <head>
        <meta charset="utf-8" />
        <title>FireBase Example</title>
        <script src="https://www.gstatic.com/firebasejs/4.9.1/firebase.js"></script>
        <script>
          // Initialize Firebase
          var config = {
            apiKey: "AIzaSyAOSPYpgn7T_bKa6VbCaSeQlsw-3p3zqDs",
            authDomain: "yiibai-firebase.firebaseapp.com",
            databaseURL: "https://yiibai-firebase.firebaseio.com/",
            projectId: "yiibai-firebase",
            storageBucket: "yiibai-firebase.appspot.com",
            messagingSenderId: "334522625008"
          };
          firebase.initializeApp(config);
          var playersRef = firebase.database().ref("players/");
          playersRef.on("child_added", function(data, prevChildKey) {
               var newPlayer = data.val();
               //console.log("name: " + newPlayer.name);
               console.log("age: " + newPlayer.age);
               console.log("number: " + newPlayer.number);
               console.log("Previous Player: " + prevChildKey);
            });
        </script>
    </head>
<body>

執(zhí)行上面示例代碼，得到以下結(jié)果。

child_changed

這個事件類型在數(shù)據(jù)改變時被觸發(fā)。

示例

考慮下面的例子。

var playersRef = firebase.database().ref("players/");

playersRef.on("child_changed", function(data) {
   var player = data.val();
   console.log("The updated player age is " + player.age);
});

可以在Firebase控制臺中將Amanda的age字段的值由21更改為28以獲取更新。

child_removed

假設(shè)原始數(shù)據(jù)如下 -

如果想獲得已刪除數(shù)據(jù)的訪問權(quán)限，可以使用child_removed事件類型。

示例

var playersRef = firebase.database().ref("players/");

playersRef.on("child_removed", function(data) {
   var deletedPlayer = data.val();
   console.log(deletedPlayer.age + " has been deleted");
});

上面示例中，假設(shè)我們刪除索引號為:100，名字為:Maxsu的一行數(shù)據(jù)。則 -

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