>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3590553. --> Reported by: [effulgentsia](https://www.drupal.org/user/78040) Related to !1113 >>> <h3 id="overview">Overview</h3> <p><code>window</code> only exists in browsers.</p> <h3 id="proposed-resolution">Proposed resolution</h3> <ul> <li>For accessing global variables, replace <code>window.</code> with <code>globalThis.</code>.</li> <li>Call <code>postMessage()</code> only when <code>window</code> exists. It's only used for the in-browser code editor so doesn't need to happen in non-browser environments.</li> </ul> <h3 id="ui-changes">User interface changes</h3>