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

{[ if (o.show_spoiler_button)  { ]}
<!-- XXX: This markup is also in src/templates/toolbar.html -->
<li class="toggle-compose-spoiler">
    <a class="
        {[ if (o.sending_spoiler)  { ]} icon-eye-blocked {[ } ]}
        {[ if (!o.sending_spoiler)  { ]} icon-eye {[ } ]}"
        title="{{ o.title }}"></a>
</li>
{[ } ]}