javascript - 传单实时 : SyntaxError: JSON. 解析:意外字符

Question

我有一张使用传单实时的 map 。

我按照github上的描述实时设置了传单。使用示例中的 url 效果很好，但是当我直接使用 json 字符串时，我会收到以下错误消息:

SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data undefined leaflet-realtime.min.js:4:3695

代码如下所示:

var geojsonFeature = {"geometry": {"type": "Point", "coordinates": [-64.90913344523922, 31.274686201725011]}, "type": "Feature", "properties": {}};


    var map = L.map('map', 
        {
            center: [<?php echo $StartNorth; ?>, <?php echo $StartEast; ?>],
            zoom: <?php echo $StartZoomLevel; ?>,
            layers: [BasemapAT_basemap, geoJSONLayerNone],

            zoomControl: false,

            contextmenu: true,
            contextmenuWidth: 200,
            contextmenuItems: [{
                text: 'Koordinaten anzeigen',
                callback: showCoordinates
            }, {
                text: 'Karte hier zentrieren',
                callback: centerMap
            }, '-', {
                text: 'Zoom in',
                icon: 'assets/leaflet-contextmenu/dist/images/zoom-in.png',
                callback: zoomIn
            }, {
                text: 'Zoom out',
                icon: 'assets/leaflet-contextmenu/dist/images/zoom-out.png',
                callback: zoomOut
            }]
        }
    )
        realtime = L.realtime({
        geojsonFeature,
        //url: 'https://wanderdrone.appspot.com/',
        crossOrigin: true,
        type: 'json'
    }, {
        interval: 3 * 1000,
            pointToLayer: function (feature, latlng) {
            return L.marker(latlng, {
                'icon': L.icon({
                    iconUrl: 'leaflet/images/marker-icon-vehicle.png',
                        iconSize:       [16, 16],
                        iconAnchor:     [1, 8],
                        popupAnchor:    [7, 0]
                })
            });
        }}).addTo(map);

理论上它应该有效，但我无法解释为什么不行。有人可以给我提示吗？

Answer 1

文档指出:

The source can be one of:

1. a string with the URL to get data from
2. an options object that is passed to fetch for fetching the data
3. a function in case you need more freedom.

In case you use a function, the function should take two callbacks as arguments: fn(success, error), with the callbacks:

1. a success callback that takes GeoJSON as argument: success( features)
2. an error callback that should take an error object and an error message (string) as argument: error( error, message)

根据文档，您尝试的内容作为来源无效。您可以通过使用函数来做到这一点。或者还有:

update(<GeoJSON> featureData?)

这是您可以用来传递数据的方法。