title: Sort object array by string property value
body: <p>I have an array of JavaScript objects</p>
  <pre><code>let data = [
        { type: 'account', title: 'Robb', subscription: 'ESSENTIAL' },
        { type: 'account', title: 'Bran', subscription: 'ESSENTIAL' },
        { type: 'account', title: 'Arya', subscription: 'FREE' },
        { type: 'article', title: 'The Wall' },
        { type: 'account', title: 'Tyrion', subscription: 'ESSENTIAL' },
      ];
  </code></pre>
  <p>The array is already sorted. I want to sort it again by subscription. The requirement is to show ESSENTIAL accounts at the top and leave others as they are. Note that some objects does not have a <code>subscription</code> property.</p>