lockfiles.  That is, it is <code>lockfileVersion: 3</code>, rather than
<code>lockfileVersion: 2</code>.</p>
<h3 id="handling-old-lockfiles">Handling Old Lockfiles</h3>
<p>When npm detects a lockfile from npm v6 or before during the package
installation process, it is automatically updated to fetch missing
information from either the <code>node_modules</code> tree or (in the case of empty
<code>node_modules</code> trees or very old lockfile formats) the npm registry.</p>
<h3 id="file-format">File Format</h3