{namespace em=TYPO3\CMS\Extensionmanager\ViewHelpers}
<em:format.jsonEncode additionalAttributes="{dependencies:dependencies,
url:'{f:uri.action(action:\"installFromTer\", controller:\"Download\", arguments:\"{extension:extension.uid, format:\'json\'}\")}',
message: '{message}',
hasErrors: '{hasErrors}',
hasDependencies: '{hasDependencies}',
title: '{title}'
}" />
