Fixing TinyMCE Anchor Links That Jump to the Home Page

Older TinyMCE integrations in Evolution CMS could generate anchor links that behaved poorly on the frontend, especially when relative fragment links such as #section were interpreted without the current page path.

The fix from the article

Create a small plugin on OnWebPagePrerender that rewrites fragment-only links into full links for the current resource.

switch ($modx->Event->name) {
    case 'OnWebPagePrerender':
        if ($modx->documentIdentifier != $modx->config['site_start'] && !empty($modx->documentIdentifier)) {
            $modx->documentOutput = str_replace(
                'href="#',
                'href="' . $modx->makeUrl($modx->documentIdentifier) . '#',
                $modx->documentOutput
            );
        }
        break;
}

Why this worked

It forced anchor links to resolve against the actual page URL instead of leaving the browser to guess based on the current routing context.