title: Parse string into an array when it's already written like an array
body: <p>I'm reading a text file with XMLHttpRequest. Its contents are:</p>
  
  <pre><code>['01.html', '02.html', '03.html']
  </code></pre>
  
  <p><code>xhr.responseText</code> is a string, and I can't cast it into an array, even though it is written precisely like an array.</p>
  
  <p>In particular, <code>JSON.parse</code> does not work, because the strings here use single quotes (<code>'...'</code>), while the JSON grammar only recognizes string with double quotes (<code>"..."</code>).</p>