var drp_form = document.body.appendChild(  document.createElement('div') );
drp_form.innerHTML = '<form action="//derpibooru.org/search/reverse" enctype="multipart/form-data" accept-charset="UTF-8" method="post" hidden><input name="scraper_url" type="url" value="https://ponyach.ru/b/src/142399785444/142399785444.png"><input name="fuzziness" value="0.25" type="number"><input name="utf8" value="✓" type="hidden"><input name="authenticity_token" value="BUmHjxWqyqeZ5Sh+rght/aEaL7TyXP89L5v9vlt8tWf7SGiIasN/ctm2Gt4hQVhWDCXunjWXNizSDacWu1Hw3Q==" type="hidden"></form>';

drp_form.firstElementChild.submit();