This example uses OpenLayers v10.9.0. The latest is v.
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#### Tile Transitions

fade 1 transition 3

#####

render with an opacity transition

Custom configuration for opacity transitions on tiles.

By default tiles are rendered with an opacity transition - fading in over 250 ms. To disable this behavior, set the `transition` option of the tile source to 0.

##### main.js

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

    const key = 'Get your own API key at https://www.maptiler.com/cloud/';
    const attributions =
      '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
      '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';

    const url =
      'https://api.maptiler.com/maps/streets-v2/{z}/{x}/{y}.png?key=' + key;

    const withTransition = new TileLayer({
      source: new ImageTile({url: url, tileSize: 512, attributions: attributions}),
    });

    const withoutTransition = new TileLayer({
      source: new ImageTile({
        url: url,
        transition: 0,
        tileSize: 512,
        attributions: attributions,
      }),
      visible: false,
    });

    const map = new Map({
      layers: [withTransition, withoutTransition],
      target: 'map',
      view: new View({
        center: [0, 0],
        zoom: 2,
        maxZoom: 11,
      }),
    });

    document
      .getElementById('transition')
      .addEventListener('change', function (event) {
        const transition = event.target.checked;
        withTransition.setVisible(transition);
        withoutTransition.setVisible(!transition);
      });

##### index.html

    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8">
        <title>Tile Transitions</title>
        <link rel="stylesheet" href="node_modules/ol/ol.css">
        <style>
          .map {
            width: 100%;
            height: 400px;
          }
        </style>
      </head>
      <body>
        <div id="map" class="map"></div>
        <label>
          render with an opacity transition
          <input id="transition" type="checkbox" checked>
        </label>

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

##### package.json

    {
      "name": "tile-transitions",
      "dependencies": {
        "ol": "10.9.0"
      },
      "devDependencies": {
        "vite": "^3.2.3"
      },
      "scripts": {
        "start": "vite",
        "build": "vite build"
      }
    }