Kemono Party attachment download fixer

kemono_attachment_fix.user.js

// ==UserScript==
// @name        Kemono Party attachment download fixer
// @author      anadius
// @namespace   anadius.hermietkreeft.site
// @match       https://kemono.party/*
// @version     1.0.0
// @grant       GM.xmlHttpRequest
// @run-at      document-end
// ==/UserScript==

const downloadBlob = (blob, name) => {
  const link = document.createElement("a");
  const url = window.URL.createObjectURL(blob);
  link.href = url;
  link.download = name;
  document.body.appendChild(link);
  link.click();
  window.URL.revokeObjectURL(url);
  link.remove();
};

const downloadAttachment = async event => {
  event.preventDefault();

  const attachment = event.target;

  GM.xmlHttpRequest({
    method: "GET",
    url: attachment.href,
    responseType: "blob",
    onload: response => {
      downloadBlob(response.response, decodeURIComponent(attachment.download));
      attachment.removeAttribute("data-progress");
    },
    onprogress: response => {
      let progress;
      if(response.lengthComputable) {
        progress = `${(response.loaded / response.total * 100).toFixed(2)}%`;
      }
      else {
        progress = `${response.loaded} bytes loaded`;
      }
      attachment.setAttribute("data-progress", progress);
    },
  });
};

document.styleSheets[0].addRule(".post__attachment-link:after","color: red; content: attr(data-progress)");

for(const attachment of document.querySelectorAll(".post__attachment-link")) {
  attachment.addEventListener("click", downloadAttachment);
}