This example uses OpenLayers v10.9.0. The latest is v.
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#### Vector Label Decluttering

vector 86 decluttering 2 declutter 2 labels 3

#####

Label decluttering on polygons.

Decluttering is used to avoid overlapping labels. The `overflow: true` setting on the text style makes it so labels that do not fit within the bounds of a polygon are also considered for decluttering.

##### main.js

    import Map from 'ol/Map.js';
    import View from 'ol/View.js';
    import GeoJSON from 'ol/format/GeoJSON.js';
    import VectorLayer from 'ol/layer/Vector.js';
    import {fromLonLat} from 'ol/proj.js';
    import VectorSource from 'ol/source/Vector.js';
    import Fill from 'ol/style/Fill.js';
    import Stroke from 'ol/style/Stroke.js';
    import Style from 'ol/style/Style.js';
    import Text from 'ol/style/Text.js';

    const map = new Map({
      target: 'map',
      view: new View({
        center: fromLonLat([-100, 38.5]),
        zoom: 4,
      }),
    });

    const labelStyle = new Style({
      text: new Text({
        font: '12px Calibri,sans-serif',
        overflow: true,
        fill: new Fill({
          color: '#000',
        }),
        stroke: new Stroke({
          color: '#fff',
          width: 3,
        }),
      }),
    });
    const countryStyle = new Style({
      fill: new Fill({
        color: 'rgba(255, 255, 255, 0.6)',
      }),
      stroke: new Stroke({
        color: '#319FD3',
        width: 1,
      }),
    });
    const style = [countryStyle, labelStyle];

    const vectorLayer = new VectorLayer({
      background: 'white',
      source: new VectorSource({
        url: 'https://openlayers.org/data/vector/us-states.json',
        format: new GeoJSON(),
      }),
      style: function (feature) {
        const label = feature.get('name').split(' ').join('\n');
        labelStyle.getText().setText(label);
        return style;
      },
      declutter: true,
    });

    map.addLayer(vectorLayer);

##### index.html

    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8">
        <title>Vector Label Decluttering</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>

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

##### package.json

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