This example uses OpenLayers v10.9.0. The latest is v.
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#### Custom Controls

custom 6 control 3

#####

Shows how to create custom controls.

This example creates a "rotate to north" button.

##### main.js

    import Map from 'ol/Map.js';
    import View from 'ol/View.js';
    import Control from 'ol/control/Control.js';
    import {defaults as defaultControls} from 'ol/control/defaults.js';
    import TileLayer from 'ol/layer/Tile.js';
    import OSM from 'ol/source/OSM.js';

    //
    // Define rotate to north control.
    //

    class RotateNorthControl extends Control {
      /**
       * @param {Object} [opt_options] Control options.
       */
      constructor(opt_options) {
        const options = opt_options || {};

        const button = document.createElement('button');
        button.innerHTML = 'N';

        const element = document.createElement('div');
        element.className = 'rotate-north ol-unselectable ol-control';
        element.appendChild(button);

        super({
          element: element,
          target: options.target,
        });

        button.addEventListener('click', this.handleRotateNorth.bind(this), false);
      }

      handleRotateNorth() {
        this.getMap().getView().setRotation(0);
      }
    }

    //
    // Create map, giving it a rotate to north control.
    //

    const map = new Map({
      controls: defaultControls().extend([new RotateNorthControl()]),
      layers: [
        new TileLayer({
          source: new OSM(),
        }),
      ],
      target: 'map',
      view: new View({
        center: [0, 0],
        zoom: 3,
        rotation: 1,
      }),
    });

##### index.html

    <!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8">
        <title>Custom Controls</title>
        <link rel="stylesheet" href="node_modules/ol/ol.css">
        <style>
          .map {
            width: 100%;
            height: 400px;
          }
          .rotate-north {
            top: 65px;
            left: .5em;
          }
          .ol-touch .rotate-north {
            top: 80px;
          }
        </style>
      </head>
      <body>
        <div id="map" class="map"></div>

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

##### package.json

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