title: Create multiple query keys by URL & URLSearchParams
body: <p>I want to create url value which have multiple key values in JavaScript.</p>
  <p>If I do like this,</p>
  <pre class="lang-js prettyprint-override"><code>    const url = new URL('http://example.com/hoge');
      url.search = new URLSearchParams(['a': ['b', 'c'], 'd': 'e']);
      console.log(url.href);
  </code></pre>
  <p>I achieved</p>
  <pre><code>http://example.com/hoge?a=b,c&amp;d=e
  </code></pre>
  <p>But I want to have is</p>
  <pre><code>http://example.com/hoge?a=b&amp;a=c&amp;d=e
  </code></pre>
  <p>How can I get it?</p>