title: Array of objects map with dynamic column names
body: <p>Say, I have an array of objects with country, state, city.. I would like to use .map on this array to get unique countries or states or cities depending on my requirements.. how do I write one method that accepts one column name that I would like to map and return result accordingly.</p>
  <pre><code>GetUniqueValues(colName) { // colName could be county or state
  const uniqueVals = Array.from(new Set(this.myArray.map(item =&gt; item.country))); // how do I include colName here without writing item.country or item.state as I have many other fields to map
  return uniqueVals;
  }
  </code></pre>