Question

我在Firebase上很新，我试图在Firebase的文档中使用本教程： https://www.firebase.com/docs/open-data/transit.html

但我真的被卡住了......或者更好，我完全迷失了。屏幕上没有任何内容。

<head>
<script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true"></script>
<script src="https://cdn.firebase.com/js/client/1.0.18/firebase.js"></script>
<script src="https://www.firebase.com/resources/js/publicdata/transit.js"></script>
    <script>
    // Lookup all buses on line "X".
    var transitLine = "5";
    var transitRef = new Firebase("https://publicdata-transit.firebaseio.com/ttc");
    var lineIndex = transitRef.child("routes").child(transitLine);

    lineIndex.on("child_added", function (snapshot) {
        var id = snapshot.name();
        transitRef.child("routes").child(id).on("vehicles", busUpdated);
    });
    lineIndex.on("child_removed", function (snapshot) {
        var id = snapshot.name();
        transitRef.child("routes").child(id).off("vehicles", busUpdated);
    });

    function busUpdated(snapshot) {
        // Bus line "X" changed location.
        var info = snapshot.val();
        // Retrieve latitude/longitude with info.lat/info.lon.
    }
</script>
</head>

<body>
<div id="map_canvas" style="position:relative;width:600px;height:400px; border: 1px solid #ccc; margin: 0 auto;"></div>
</body>

有人知道我做错了什么？

Answer 1

原始剧本中有两个错误：

您正在观看错误的顶级参考（transit而不是routes）
您正在收听不存在的活动（vehicles而不是value）

此代码应该更好用：

// Lookup all buses on line "X".
var transitLine = "5";
var transitRef = new Firebase("https://publicdata-transit.firebaseio.com/ttc");
var lineIndex = transitRef.child("routes").child(transitLine);

lineIndex.on("child_added", function (snapshot) {
    var id = snapshot.name();
    transitRef.child("vehicles").child(id).on("value", busUpdated);
});
lineIndex.on("child_removed", function (snapshot) {
    var id = snapshot.name();
    transitRef.child("vehicles").child(id).off("value", busUpdated);
});

function busUpdated(snapshot) {
    // Bus line "X" changed location.
    var info = snapshot.val();
    console.log(info);
    // Retrieve latitude/longitude with info.lat/info.lon.
}

小提琴：http://jsfiddle.net/tr5P7/

Firebase - 遵循公交数据集教程？

1 个答案: