title: Map nested array with JavaScript
body: <p>I'm trying to map a nested array using .map(), so I could display and pinpoint all London underground locations in a map.</p>
  
  <pre><code>this.undergroundGeoJson = [
          {
              'type': 'FeatureCollection',
  
              'crs': { 'type': 'name', 'properties': { 'name': 
              'urn:ogc:def:crs:OGC:1.3:CRS84' } },
  
              'features': [
                  {
                      'type': 'Feature',
                      'geometry': {
                          'type': 'Point',
                          'coordinates': [-0.278126, 51.5025]
                      },
                      'properties': {
                          'name': 'Acton Town'
                      }
                  },
                  {
                      'type': 'Feature',
                      'geometry': {
                          'type': 'Point',
                          'coordinates': [-0.263033174, 51.50883531]
                      },
                      'properties': {
                          'name': 'Acton Central'
                      }
                  },
                  {
                      'type': 'Feature',
                      'geometry': {
                          'type': 'Point',
                          'coordinates': [-0.262879534, 51.50856013]
                      },
                      'properties': {
                          'name': 'Acton Central'
                      }
                  }
             }
         ]
  </code></pre>
  
  <p>I need the coordinates array elements down in the geometry obj.</p>
  
  <p>this is my code so far...</p>
  
  <pre><code>@computed
      get undergroundLatLongs() {
      return this.undergroundGeoJson.map((u) =&gt;
      [u.features.geometry.coordinates[0], 
      u.features.geometry.coordinates[1]]);
  }
  </code></pre>
  
  <p>and this is the error log...</p>
  
  <pre><code>Uncaught TypeError: Cannot read property 'coordinates' of undefined
  </code></pre>
  
  <p>any help welcomed. </p>