Edit

Example of a localized OpenStreetMap map with a custom tile server and a custom attribution.

The base layer is OpenCycleMap with an overlay from OpenSeaMap.

main.js
import 'ol/ol.css';
import Map from 'ol/Map';
import OSM, {ATTRIBUTION} from 'ol/source/OSM';
import TileLayer from 'ol/layer/Tile';
import View from 'ol/View';

var openCycleMapLayer = new TileLayer({
  source: new OSM({
    attributions: [
      'All maps © <a href="https://www.opencyclemap.org/">OpenCycleMap</a>',
      ATTRIBUTION ],
    url:
      'https://{a-c}.tile.thunderforest.com/cycle/{z}/{x}/{y}.png' +
      '?apikey=Your API key from http://www.thunderforest.com/docs/apikeys/ here',
  }),
});

var openSeaMapLayer = new TileLayer({
  source: new OSM({
    attributions: [
      'All maps © <a href="http://www.openseamap.org/">OpenSeaMap</a>',
      ATTRIBUTION ],
    opaque: false,
    url: 'https://tiles.openseamap.org/seamark/{z}/{x}/{y}.png',
  }),
});

var map = new Map({
  layers: [openCycleMapLayer, openSeaMapLayer],
  target: 'map',
  view: new View({
    maxZoom: 18,
    center: [-244780.24508882355, 5986452.183179816],
    zoom: 15,
  }),
});
index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Localized OpenStreetMap</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script src="main.js"></script>
  </body>
</html>
package.json
{
  "name": "localized-openstreetmap",
  "dependencies": {
    "ol": "6.4.3"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}