title: Calculate array with operators
body: <p>I am building a calculator app. Where I store input values in array with operators.
  e.g</p>
  <pre><code>let arr = ['2', '3', '+', '7', '-', '8', '*', '2']
  </code></pre>
  <p>I can't figure out how to handle operator by looping over to get result either 44 or 14 depends on logic.</p>