OpenLayers - OSM raster tiles

OpenLayers map using Proj4js reprojecting OSM raster tiles.

HTML:

<div id='map'></div>

Javascript:

proj4.defs('EPSG:8857', '+proj=eqearth +lon_0=0 +x_0=0 +y_0=0 +R=6371008.7714 +units=m +no_defs +type=crs');
ol.proj.proj4.register(proj4);

const extent = [-17243959.06, -17243959.06, 17243959.06, 17243959.06];

const map = new ol.Map({
  layers: [
    new ol.layer.Tile({
      source: new ol.source.OSM(),
    }),
  ],
  target: 'map',
  view: new ol.View({
    center: [0, 0],
    projection: 'EPSG:8857',
    extent: extent,
    zoom: 0
  }),
});

map.addControl(new ol.control.ScaleLine());

Header:

<script src="https://cdn.jsdelivr.net/npm/ol@9.1.0/dist/ol.js"></script>
<link href="https://cdn.jsdelivr.net/npm/ol@9.1.0/ol.min.css" rel="stylesheet">
<script src="https://cdn.jsdelivr.net/npm/proj4@2.11.0/dist/proj4.min.js"></script>