title: Why do I get `undefined` when using `document.getElementsByClassName(...).value`?
body: <p>Why do I get <code>undefined</code> as result of <code>console.log(tes_val)</code>? How can I fix it?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var tes = document.getElementsByClassName('a_b_1');
  var tes_val = tes.value;
  console.log(tes_val);</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;input type="hidden" class="a_b_1" name="c_d_1" value="1|2|3"&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Thank you.</p>