Lazy Source

Example of setting a layer source after construction.

Typically, the source for a layer is provided to the layer constructor. If you need to set a layer source after construction, this can be done with the layer.setSource() method.

The layer in the map above is constructed with no source. Use the links below to set/unset the layer source. A layer is not rendered until its source is set.

main.js

import Map from 'ol/Map.js';
import OSM from 'ol/source/OSM.js';
import TileLayer from 'ol/layer/Tile.js';
import View from 'ol/View.js';

const source = new OSM();

const layer = new TileLayer();

const map = new Map({
  layers: [layer],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2,
  }),
});

document.getElementById('set-source').onclick = function () {
  layer.setSource(source);
};

document.getElementById('unset-source').onclick = function () {
  layer.setSource(null);
};

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Lazy Source</title>
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
       button.code {
         font-family: Monaco,Menlo,Consolas,"Courier New",monospace;
         font-size: 12px;
         padding: 5px;
         margin: 0 5px;
       }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <button id="set-source" class="code">layer.setSource(source)</button>
    <button id="unset-source" class="code">layer.setSource(null)</button>

    <script type="module" src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "lazy-source",
  "dependencies": {
    "ol": "9.1.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}