GreasyFork: download script button

If you have a script manager and you want to download some script without installing it, this script will help
当前为 2021-11-30 提交的版本，查看最新版本。
换行
// ==UserScript==
// @name         GreasyFork: download script button
// @description  If you have a script manager and you want to download some script without installing it, this script will help
// @namespace    https://greasyforks.org/users/424058
// @version      1.1.1
// @author       Konf
// @match        https://greasyforks.org
// @include      /^http(s|):\/\/greasyforks.org\/[a-zA-Z_-]*\/scripts\/\d.*$/
// @run-at       document-end
// @resource     iconDownload https://img.icons8.com/pastel-glyph/64/ffffff/download.png
// @compatible   Chrome
// @compatible   Opera
// @compatible   Firefox
// @grant        GM_getResourceUrl
// @grant        GM.getResourceUrl
// @noframes
// ==/UserScript==

/* jshint esversion: 6 */
/* eslint-disable no-multi-spaces */

(function() {
  'use strict';

  const userLang = location.pathname.split('/')[1];
  const langStringsList = {
    'en': {
      Dl: 'Download without installing',
      unableDl: 'Unable to download the script'
    },
    'zh-CN': {
      Dl: '下载此脚本',
      unableDl: '无法下载此脚本'
    },
    'ru': {
      Dl: 'Скачать не устанавливая',
      unableDl: 'Не удалось скачать скрипт'
    }
  };
  const langStrings = langStringsList[userLang] || langStringsList.en;

  const b = document.createElement('button'); // downloadBtn
  const bIcon = document.createElement('div');
  const bParent = document.body.querySelector('div#install-area');
  const bNeighbour = document.body.querySelector('a.install-help-link');
  const installBtn = document.body.querySelector('a.install-link');

  if (!bParent || !bNeighbour || !installBtn) return;

  b.title = langStrings.Dl;
  b.className = 'tm-dsb-downloadBtn';
  bIcon.className = 'tm-dsb-downloadBtn__icon tm-dsb-downloadBtn__icon--download';
  bNeighbour.style.position = 'relative'; // shadow bugfix
  bParent.insertBefore(b, bNeighbour);
  b.appendChild(bIcon);

  let fetchingDelay = false;

  (GM.getResourceUrl || GM_getResourceUrl)('iconDownload')
  .then(downloadIconUrl => {
    addCSS(`
      .tm-dsb-downloadBtn {
        width: 43px;
        height: 38px;
        position: relative;
        padding: 0;
        vertical-align: bottom;
        cursor: pointer;
        border: none;
        outline: none;
        background: #0F750F;
        transition: box-shadow 0.2s;
      }

      .tm-dsb-downloadBtn:hover,
      .tm-dsb-downloadBtn:focus {
        box-shadow: 0 8px 16px 0 rgb(0 0 0 / 20%), 0 6px 20px 0 rgb(0 0 0 / 19%);
      }


      .tm-dsb-downloadBtn__icon {
        position: absolute;
      }

      .tm-dsb-downloadBtn__icon--download {
        width: 35px;
        height: 35px;
        top: 1px;
        left: 4px;
        background: url(${downloadIconUrl});
        background-size: contain;
      }

      .tm-dsb-downloadBtn__icon--loading,
      .tm-dsb-downloadBtn__icon--loading:after {
        border-radius: 50%;
        width: 16px;
        height: 16px;
      }

      .tm-dsb-downloadBtn__icon--loading {
        top: 6px;
        left: 8px;
        text-indent: -9999em;
        border-top: 5px solid rgba(255, 255, 255, 0.2);
        border-right: 5px solid rgba(255, 255, 255, 0.2);
        border-bottom: 5px solid rgba(255, 255, 255, 0.2);
        border-left: 5px solid #ffffff;
        -webkit-transform: translateZ(0);
        -ms-transform: translateZ(0);
        transform: translateZ(0);
        -webkit-animation: loading 1.1s infinite linear;
        animation: loading 1.1s infinite linear;
      }

      @-webkit-keyframes loading {
        0% {
          -webkit-transform: rotate(0deg);
          transform: rotate(0deg);
        }
        100% {
          -webkit-transform: rotate(360deg);
          transform: rotate(360deg);
        }
      }

      @keyframes loading {
        0% {
          -webkit-transform: rotate(0deg);
          transform: rotate(0deg);
        }
        100% {
          -webkit-transform: rotate(360deg);
          transform: rotate(360deg);
        }
      }
    `);
  });

  b.addEventListener('click', () => {
    setTimeout(() => {
      if (b === document.activeElement) document.activeElement.blur();
    }, 250);

    if (fetchingDelay) return;
    fetchingDelay = true;
    bIcon.className = 'tm-dsb-downloadBtn__icon tm-dsb-downloadBtn__icon--loading';

    fetch(installBtn.href)
      .then(res => res.blob())
      .then(blob => {
        const url = window.URL.createObjectURL(blob);
        const a = document.createElement('a');

        a.href = url;
        a.download = `${installBtn.dataset.scriptName}.user.js`;
        document.body.appendChild(a); // needed due to firefox bug
        a.click();
        a.remove();

        setTimeout(closeFetchUX, 300);
        window.URL.revokeObjectURL(url);
      })
      .catch(e => {
        setTimeout(closeFetchUX, 300);
        alert(`${langStrings.unableDl}: \n${e}`);
     });
  });


  // utils -------------------------------------------------------------

  function closeFetchUX() {
    fetchingDelay = false;
    bIcon.className = 'tm-dsb-downloadBtn__icon tm-dsb-downloadBtn__icon--download';
  }

  function addCSS(cssCode) {
    const styleEl = document.createElement("style");
    styleEl.type = "text/css";

    if (styleEl.styleSheet) {
      styleEl.styleSheet.cssText = cssCode;
    } else {
      styleEl.appendChild(document.createTextNode(cssCode));
    }

    document.getElementsByTagName("head")[0].appendChild(styleEl);

    return styleEl;
  }

  // --------------------------------------------------------------------

})();