OpenLayers: Polygon mit Koordinaten erstellen?

Hallo,

Edit: habe was anderes gefunden und damit ein Problem, siehe hier:
https://forum.openstreetmap.org/viewtopic.php?pid=665817#p665817

ich nutze bereits eine Openstreetmap mit einem Openlayer und will diese nun um einen weiteren Openlayer erweitern.
Der OpenLayer soll ein simples Polygon sein, das mit Koordinaten angegeben werden soll. Hintergrund dabei ist, dass über ein Javascript die Koordinaten für das Polygon berechnet werden, und da komme ich gerade nicht weiter.

Hier gibt es Examples für OpenLayer:
https://openlayers.org/en/latest/examples/
Dort habe ich ein Script für ein “countries”-Layer gefunden, das dem was ich will nahe kommt, also Formen nach Koordinaten overlayern. Nur müßten die Koordinaten nicht in einer externen Datei gespeichert sein, sondern direkt im Script. Ich weiß aber nicht wie man das anstellt. Einfach den Inhalt aus der externen Datei in das Script schreiben funktioniert nicht.

Das “countries”-Example:
https://openlayers.org/en/latest/examples/vector-layer.html

Die betreffende Stelle:

      var vectorLayer = new ol.layer.Vector({
        source: new ol.source.Vector({
          url: 'https://openlayers.org/en/v4.3.4/examples/data/geojson/countries.geojson',
          format: new ol.format.GeoJSON()
        }),
        style: function(feature, resolution) {
          style.getText().setText(resolution < 5000 ? feature.get('name') : '');
          return style;
        }
      });

Ausschnitt aus der countries.geojson

{"type":"FeatureCollection","features":[
{"type":"Feature","id":"AFG","properties":{"name":"Afghanistan"},"geometry":{"type":"Polygon","coordinates":[[[61.210817,35.650072],[62.230651,35.270664],[62.984662,35.404041],[63.193538,35.857166],[63.982896,36.007957],[64.546479,36.312073],[64.746105,37.111818],[65.588948,37.305217],[65.745631,37.661164],[66.217385,37.39379],[66.518607,37.362784],[67.075782,37.356144],[67.83,37.144994],[68.135562,37.023115],[68.859446,37.344336],[69.196273,37.151144],[69.518785,37.608997],[70.116578,37.588223],[70.270574,37.735165],[70.376304,38.138396],[70.806821,38.486282],[71.348131,38.258905],[71.239404,37.953265],[71.541918,37.905774],[71.448693,37.065645],[71.844638,36.738171],[72.193041,36.948288],[72.63689,37.047558],[73.260056,37.495257],[73.948696,37.421566],[74.980002,37.41999],[75.158028,37.133031],[74.575893,37.020841],[74.067552,36.836176],[72.920025,36.720007],[71.846292,36.509942],[71.262348,36.074388],[71.498768,35.650563],[71.613076,35.153203],[71.115019,34.733126],[71.156773,34.348911],[70.881803,33.988856],[69.930543,34.02012],[70.323594,33.358533],[69.687147,33.105499],[69.262522,32.501944],[69.317764,31.901412],[68.926677,31.620189],[68.556932,31.71331],[67.792689,31.58293],[67.683394,31.303154],[66.938891,31.304911],[66.381458,30.738899],[66.346473,29.887943],[65.046862,29.472181],[64.350419,29.560031],[64.148002,29.340819],[63.550261,29.468331],[62.549857,29.318572],[60.874248,29.829239],[61.781222,30.73585],[61.699314,31.379506],[60.941945,31.548075],[60.863655,32.18292],[60.536078,32.981269],[60.9637,33.528832],[60.52843,33.676446],[60.803193,34.404102],[61.210817,35.650072]]]}},
...
]}

Funktioniert nicht:

      var vectorLayer = new ol.layer.Vector({
        source: new ol.source.Vector({
{"type":"FeatureCollection","features":[{"type":"Feature","id":"AFG","properties":{"name":"Afghanistan"},"geometry":"type":"Polygon","coordinates":[[[61.210817,35.650072],[62.230651,35.270664],[62.984662,35.404041],[63.193538,35.857166],[63.982896,36.007957],[64.546479,36.312073],[64.746105,37.111818],[65.588948,37.305217],[65.745631,37.661164],[66.217385,37.39379],[66.518607,37.362784],[67.075782,37.356144],[67.83,37.144994],[68.135562,37.023115],[68.859446,37.344336],[69.196273,37.151144],69.518785,37.608997],[70.116578,37.588223],[70.270574,37.735165],[70.376304,38.138396],70.806821,38.486282],[71.348131,38.258905],[71.239404,37.953265],[71.541918,37.905774],[71.448693,37.065645],[71.844638,36.738171],[72.193041,36.948288],[72.63689,37.047558],[73.260056,37.495257],[73.948696,37.421566],[74.980002,37.41999],[75.158028,37.133031],[74.575893,37.020841],[74.067552,36.836176],[72.920025,36.720007],[71.846292,36.509942],[71.262348,36.074388],[71.498768,35.650563],[71.613076,35.153203],[71.115019,34.733126],[71.156773,34.348911],[70.881803,33.988856],[69.930543,34.02012],[70.323594,33.358533],[69.687147,33.105499],[69.262522,32.501944],[69.317764,31.901412],[68.926677,31.620189],[68.556932,31.71331],[67.792689,31.58293],[67.683394,31.303154],[66.938891,31.304911],[66.381458,30.738899],[66.346473,29.887943],[65.046862,29.472181],[64.350419,29.560031],[64.148002,29.340819],[63.550261,29.468331],[62.549857,29.318572],[60.874248,29.829239],[61.781222,30.73585],[61.699314,31.379506],[60.941945,31.548075],[60.863655,32.18292],[60.536078,32.981269],[60.9637,33.528832],[60.52843,33.676446],[60.803193,34.404102],[61.210817,35.650072]]]}}]},
          format: new ol.format.GeoJSON()
        }),
        style: function(feature, resolution) {
          style.getText().setText(resolution < 5000 ? feature.get('name') : '');
          return style;
        }
      });