xmpp.chapril.org-conversejs/src/templates/message.html

<div class="message chat-message {{{o.extra_classes}}}" data-isodate="{{{o.isodate}}}" data-msgid="{{{o.msgid}}}">
    <span class="chat-msg-author chat-msg-{{{o.sender}}}">{{{o.time}}} {{{o.username}}}:&nbsp;</span>
    <span class="chat-msg-content"><!-- message gets added here via renderMessage --></span>
</div>