This example uses OpenLayers v10.9.0. The latest is v.
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#### Vector Clipping Layer

clipping 2 openstreetmap 22 vector 86

#####

Vector Clipping Layer example

Example of a clipping layer based on a vector source

##### main.js

    import Map from 'ol/Map.js';
    import View from 'ol/View.js';
    import GeoJSON from 'ol/format/GeoJSON.js';
    import TileLayer from 'ol/layer/Tile.js';
    import VectorLayer from 'ol/layer/Vector.js';
    import {fromLonLat} from 'ol/proj.js';
    import {getVectorContext} from 'ol/render.js';
    import OSM from 'ol/source/OSM.js';
    import StadiaMaps from 'ol/source/StadiaMaps.js';
    import VectorSource from 'ol/source/Vector.js';
    import Fill from 'ol/style/Fill.js';
    import Style from 'ol/style/Style.js';

    //A distinct className is required to use another canvas for the background
    const background = new TileLayer({
      className: 'toner',
      source: new StadiaMaps({
        layer: 'stamen_toner',
      }),
    });

    const base = new TileLayer({
      source: new OSM(),
    });

    const clipLayer = new VectorLayer({
      style: null,
      source: new VectorSource({
        url: './data/geojson/switzerland.geojson',
        format: new GeoJSON(),
      }),
    });

    //Giving the clipped layer an extent is necessary to avoid rendering when the feature is outside the viewport
    clipLayer.getSource().on('addfeature', function () {
      base.setExtent(clipLayer.getSource().getExtent());
    });

    const style = new Style({
      fill: new Fill({
        color: 'black',
      }),
    });

    base.on('postrender', function (e) {
      const vectorContext = getVectorContext(e);
      e.context.globalCompositeOperation = 'destination-in';
      clipLayer.getSource().forEachFeature(function (feature) {
        vectorContext.drawFeature(feature, style);
      });
      e.context.globalCompositeOperation = 'source-over';
    });

    const map = new Map({
      layers: [background, base, clipLayer],
      target: 'map',
      view: new View({
        center: fromLonLat([8.23, 46.86]),
        zoom: 7,
      }),
    });

##### index.html

    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8">
        <title>Vector Clipping Layer</title>
        <link rel="stylesheet" href="node_modules/ol/ol.css">
        <style>
          .map {
            width: 100%;
            height: 400px;
          }
          #map {
            background: transparent;
          }
        </style>
      </head>
      <body>
        <div id="map" class="map"></div>

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

##### package.json

    {
      "name": "layer-clipping-vector",
      "dependencies": {
        "ol": "10.9.0"
      },
      "devDependencies": {
        "vite": "^3.2.3"
      },
      "scripts": {
        "start": "vite",
        "build": "vite build"
      }
    }