地图容器找不到带有svelte的传单

Question

下面是我的代码。我正在用一张传单画一张用Svelte的曲线图。但我得到一个错误“地图未定义”。我该怎么解决这个？

<script>
    import L from 'leaflet';
    let map;
    map = L.map("mapDemo", {
  minZoom: 4,
  maxZoom: 6
});

map.zoomControl.setPosition("bottomright");
var bounds = [
  [-10, -10],
  [10, 10]
];
map.fitBounds(bounds);
var markers = {
  id1: { title: "Marker 1", coords: [1, 0], description: "Text for marker 1" },
  id2: { title: "Marker 2", coords: [4, 2], description: "Text for marker 2" },
  id3: { title: "Marker 3", coords: [8, 8], description: "Text for marker 3" }
};

var layers = L.layerGroup().addTo(map);
var titlesList = [];
var idToLayer = {};
var titleToId = {};
var idToTitle = {};
var idToText = {};

var markerOnClick = function () {
  var mId = this.options.markerId;
};

$:each(markers, function (key, val) {
  var markerOptions = {
    markerId: key,
    markerTitle: val["title"],
    markerText: val["description"]
  };

  var marker = L.marker(val["coords"], markerOptions).addTo(map);
  var popupContent = val["title"];
  // Bind popup to marker click
  marker.bindPopup(popupContent);
});

</script>
  <div id="mapDemo">
  </div>

此外，我想添加一个图像作为背景，坐标绘制在给定的图像上。

Answer 1

您应该将传单初始化代码包装在onmount中。脚本标记在元素呈现到DOM之前运行，因此mapDemo元素还不存在。

我也不确定您要用$:each做什么--我想您要找的是object.entries（标记）.foreach(([key,val])=>{})。

这是您的脚本标签与onMount和每个重写。

<script>
import { onMount } from 'svelte';
import L from 'leaflet';
let map;

onMount(() => {
    map = L.map("mapDemo", {
        minZoom: 4,
        maxZoom: 6
    });

    map.zoomControl.setPosition("bottomright");
    var bounds = [
        [-10, -10],
        [10, 10]
    ];
    map.fitBounds(bounds);
    var markers = {
        id1: {
            title: "Marker 1",
            coords: [1, 0],
            description: "Text for marker 1"
        },
        id2: {
            title: "Marker 2",
            coords: [4, 2],
            description: "Text for marker 2"
        },
        id3: {
            title: "Marker 3",
            coords: [8, 8],
            description: "Text for marker 3"
        }
    };
    var layers = L.layerGroup().addTo(map);
    var titlesList = [];
    var idToLayer = {};
    var titleToId = {};
    var idToTitle = {};
    var idToText = {};

    var markerOnClick = function() {
        var mId = this.options.markerId;
    };

    Object.entries(markers).forEach(([key, val]) => {
        var markerOptions = {
            markerId: key,
            markerTitle: val["title"],
            markerText: val["description"]
        };

        var marker = L.marker(val["coords"], markerOptions).addTo(map);
        var popupContent = val["title"];
        // Bind popup to marker click
        marker.bindPopup(popupContent);
    });
})
</script>