html tags in attachment js incorrectly escaped

I've been hitting a problem where adjusting content in the alter content hook has stumbled on an html error. The problem turns out to be because the closing tags below should be '<\/div>' not '</div>. After fixing this I was still able to successfully add & delete (& decide not to delete) attachment-type custom fields from an event.

var confirmMsg = '<div>

{/literal}{ts escape="js"}Are you sure you want to delete attachment: {/ts}{literal}' + fileName + '  <a href="#" onclick="deleteAttachment( \'' + postURLData + '\',' + fileID + ',\'' + divName + '\', \'' + divFile + '\' ); return false;" style="text-decoration: underline;">{/literal}

</div><div>

{ts escape='js'}Yes{/ts}{literal}</a>   <a href="#" onclick="hideStatusAttachment( \'' + divName + '\' ); return false;" style="text-decoration: underline;">{/literal}{ts escape='js'}

No

{/ts} {literal}

</a></div>';

The reason I care about this is that altering the html in the alterContent hook is the only way I currently have of dealing with multiple extensions wanting to alter the same settings form. The entity settings extension adds the settings for the other extensions by loading & resaving the dom object. It is a bit slower but it's only on admin forms.