Greasemonkey: GM_download - polyfill

GM_download_polyfill.js

/*
 * GM_download() polyfill
 *
 * A polyfill to make your userscript supports GM_download().
 *
 * Inspired by:
 *   https://tampermonkey.net/documentation.php?ext=dhdg#GM_download
 *
 * Supported:
 *   onabort
 *
 * Not supported:
 *   saveAs
 *
 * Contributor(s):
 *   ccloli (original author)
 *   Jan Biniok (the blacklist and whitelist from Tampermonkey)
 *   janekptacijarabaci
 *
 */

// *****************************************************************************

const API = {
  "name": {
    "basic": "GM_download",
    "fully": "GM_download()",
  },
  "nameInternal": {
    "basic": "GM_xmlhttpRequest",
    "fully": "GM_xmlhttpRequest()",
  },
};

// *****************************************************************************

// User settings.

const LOCALE = {
  "_default": "en-US",
  "_enforce": null,
  "cs": {
    "error": {
      "download": {
        "error": API.name.fully
            + ":%1",
        "failed": API.name.fully
            + " se nezdařilo.%1",
        "noUrl": API.name.fully
            + ": url nenalezeno.%1",
        "onabortIsNotFunction": API.name.fully
            + ": details.onabort není funkce!",
        "onerrorIsNotFunction": API.name.fully
            + ": details.onerror není funkce!",
        "onloadIsNotFunction": API.name.fully
            + ": details.onload není funkce!",
        "onprogressIsNotFunction": API.name.fully
            + ": details.onprogress není funkce!",
        "ontimeoutIsNotFunction": API.name.fully
            + ": details.ontimeout není funkce!",
        "xmlhttpRequest": {
          "require": API.nameInternal.fully
              + ' - typeof: "%1".'
              + "\n"
              + 'Nastavte "@grant '
              + API.nameInternal.basic
              + '" v "metadata block".',
        },
      },
    },
    "file": {
      "name": "soubor",
      // It should be on the whitelist.
      "extension": "bin",
    },
  },
  "en-US": {
    "error": {
      "download": {
        "error": API.name.fully
            + ":%1",
        "failed": API.name.fully
            + " failed:%1",
        "noUrl": API.name.fully
            + ": url not found.%1",
        "onabortIsNotFunction": API.name.fully
            + ": details.onabort is not a function!",
        "onerrorIsNotFunction": API.name.fully
            + ": details.onerror is not a function!",
        "onloadIsNotFunction": API.name.fully
            + ": details.onload is not a function!",
        "onprogressIsNotFunction": API.name.fully
            + ": details.onprogress is not a function!",
        "ontimeoutIsNotFunction": API.name.fully
            + ": details.ontimeout is not a function!",
        "xmlhttpRequest": {
          "require": API.nameInternal.fully
              + ' - typeof: "%1".'
              + "\n"
              + 'Set "@grant '
              + API.nameInternal.basic
              + '" at "metadata block".',
        },
      },
    },
    "file": {
      "name": "filename",
      // It should be on the whitelist.
      "extension": "bin",
    },
  },
};

const NAME_EXTENSION_BLACKLIST = false;

const NAME_EXTENSION = {
  "blacklist": [
    "bat",
    "com",
    "crx",
    "exe",
    "scr",
    "sh",
  ],
  "blacklistRegexp": [
  ],
  "whitelist": [
    "7z",
    "avi",
    "bin",
    "divx",
    // "flv",
    "gif",
    "ico",
    "idx",
    "iso",
    "jpe",
    "jpeg",
    "mkv",
    "mp3",
    "mp4",
    "mpe",
    "mpeg",
    "png",
    "rar",
    "srt",
    "sub",
    "txt",
    "wav",
    "webm",
    "zip",
  ],
  "whitelistRegexp": [
    "r(ar|[0-9]{2,2})",
  ],
};

// *****************************************************************************

var _language = ((LOCALE._enforce) ? LOCALE._enforce
    : (navigator.language ? navigator.language
    : LOCALE._default));
_language = (_language in LOCALE) ? _language : LOCALE._default;

const _LOCALE = {
  "result": {
    "error": {
      "download": {
        "error": LOCALE[_language].error.download.error,
        "failed": LOCALE[_language].error.download.failed,
        "noUrl": LOCALE[_language].error.download.noUrl,
        "onabortIsNotFunction":
            LOCALE[_language].error.download.onabortIsNotFunction,
        "onerrorIsNotFunction":
            LOCALE[_language].error.download.onerrorIsNotFunction,
        "onloadIsNotFunction":
            LOCALE[_language].error.download.onloadIsNotFunction,
        "onprogressIsNotFunction":
            LOCALE[_language].error.download.onprogressIsNotFunction,
        "ontimeoutIsNotFunction":
            LOCALE[_language].error.download.ontimeoutIsNotFunction,
        "xmlhttpRequest": {
          "require": LOCALE[_language].error.download.xmlhttpRequest.require,
        },
      },
    },
    "file": {
      "name": LOCALE[_language].file.name,
      "extension": LOCALE[_language].file.extension,
    },
  },
};

const _RESULT = {
  "error": {
    "BLACKLISTED": "blacklisted",
    "NOT_SUCCEEDED": "not_succeeded",
    "NOT_WHITELISTED": "not_whitelisted",
  },
};

// *****************************************************************************

if (typeof GM_download != "function") {
  if (typeof GM_xmlhttpRequest != "function") {
    throw new Error(
        _LOCALE.result.error.download.xmlhttpRequest.require
        .replace("%1", typeof GM_xmlhttpRequest));
  }

  function GM_download(aDetailsOrUrl, aName) {
    let _functionEmpty = function () {};

    var message = "";

    var details = {
      "url": null,
      "name": _LOCALE.result.file.name + "." + _LOCALE.result.file.extension,
      "onabort": _functionEmpty,
      "onerror": _functionEmpty,
      "onload": _functionEmpty,
      "onprogress": _functionEmpty,
      "ontimeout": _functionEmpty,
    };

    var _details = {};

    if (aDetailsOrUrl) {
      if (typeof aDetailsOrUrl == "object") {
        for (let i in aDetailsOrUrl) {
          _details[i] = aDetailsOrUrl[i];
        }
      } else if (typeof aDetailsOrUrl == "string") {
        details.url = aDetailsOrUrl;
      }
    }

    if (_details.url && (typeof _details.url == "string")) {
      details.url = _details.url;
    }
    if (_details.name && (typeof _details.name == "string")) {
      details.name = _details.name;
    }
    if (_details.onabort) {
      details.onabort = _details.onabort;
    }
    if (_details.onerror) {
      details.onerror = _details.onerror;
    }
    if (_details.onload) {
      details.onload = _details.onload;
    }
    if (_details.onprogress) {
      details.onprogress = _details.onprogress;
    }
    if (_details.ontimeout) {
      details.ontimeout = _details.ontimeout;
    }

    for (let i in _details) {
      if (!(i in details)) {
        details[i] = _details[i];
      }
    }

    if (details.url == null) {
      message = "\n" + "url: " + details.url;
      message += "\n" + "name: " + details.name;
      message = _LOCALE.result.error.download.noUrl
          .replace("%1", message);
      details.onerror({
        "details": message,
        "error": _RESULT.error.NOT_SUCCEEDED,
      });

      return false;
    }

    if (typeof details.onabort != "function") {
      message = _LOCALE.result.error.download.onabortIsNotFunction; 
      message += "\n" + "url: " + details.url;
      message += "\n" + "name: " + details.name;
      details.onerror({
        "details": message,
        "error": _RESULT.error.NOT_SUCCEEDED,
      });

      return false;
    }
    if (typeof details.onerror != "function") {
      message = _LOCALE.result.error.download.onerrorIsNotFunction;
      message += "\n" + "url: " + details.url;
      message += "\n" + "name: " + details.name;
      console.error(message);

      return false;
    }
    if (typeof details.onload != "function") {
      message = _LOCALE.result.error.download.onloadIsNotFunction;
      message += "\n" + "url: " + details.url;
      message += "\n" + "name: " + details.name;
      details.onerror({
        "details": message,
        "error": _RESULT.error.NOT_SUCCEEDED,
      });

      return false;
    }
    if (typeof details.onprogress != "function") {
      message = _LOCALE.result.error.download.onprogressIsNotFunction;
      message += "\n" + "url: " + details.url;
      message += "\n" + "name: " + details.name;
      details.onerror({
        "details": message,
        "error": _RESULT.error.NOT_SUCCEEDED,
      });

      return false;
    }
    if (typeof details.ontimeout != "function") {
      message = _LOCALE.result.error.download.ontimeoutIsNotFunction;
      message += "\n" + "url: " + details.url;
      message += "\n" + "name: " + details.name;
      details.onerror({
        "details": message,
        "error": _RESULT.error.NOT_SUCCEEDED,
      });

      return false;
    }

    if (aName) {
      if (typeof aName == "string") {
        details.name = aName;
      }
    }

    let nameCheckBlacklist = false;
    if (NAME_EXTENSION_BLACKLIST && (NAME_EXTENSION.blacklist.length > 0)) {
      nameCheckBlacklist = NAME_EXTENSION.blacklist.some(function (aItem) {
        return details.name.toLowerCase().endsWith("." + aItem.toLowerCase());
      });
    }
    let nameCheckBlacklistRegexp = false;
    if (NAME_EXTENSION_BLACKLIST
        && (NAME_EXTENSION.blacklistRegexp.length > 0)) {
      nameCheckBlacklistRegexp = NAME_EXTENSION.blacklistRegexp.some(
          function (aItem) {
            return (new RegExp("\\." + aItem + "$", "i")).test(details.name);
          });
    }
    let nameCheckWhitelist = false;
    if (NAME_EXTENSION.whitelist.length > 0) {
      nameCheckWhitelist = NAME_EXTENSION.whitelist.some(function (aItem) {
        return details.name.toLowerCase().endsWith("." + aItem.toLowerCase());
      });
    }
    let nameCheckWhitelistRegexp = false;
    if (NAME_EXTENSION.whitelistRegexp.length > 0) {
      nameCheckWhitelistRegexp = NAME_EXTENSION.whitelistRegexp.some(
          function (aItem) {
            return (new RegExp("\\." + aItem + "$", "i")).test(details.name);
          });
    }

    if (NAME_EXTENSION_BLACKLIST
        && (nameCheckBlacklist || nameCheckBlacklistRegexp)) {
      details.onerror({
        "error": _RESULT.error.BLACKLISTED,
      });

      return false;
    }
    if (!nameCheckWhitelist && !nameCheckWhitelistRegexp) {
      details.onerror({
        "error": _RESULT.error.NOT_WHITELISTED,
      });

      return false;
    }

    let data = {
      "method": "GET",
      // "responseType": "arraybuffer",
      "responseType": "blob",
      "url": details.url,

      "onabort": function (aResponse) {
        details.onabort(aResponse);
      },
      "onerror": function (aResponse) {
        message = "\n" + "url: " + details.url;
        message += "\n" + "name: " + details.name;
        message = _LOCALE.result.error.download.failed
            .replace("%1", message);
        details.onerror({
          "details": message,
          "error": _RESULT.error.NOT_SUCCEEDED,
        });

        return false;
      },
      "onload": function (aResponse) {
        let separators = {
          "headers": "\n",
          "nameValue": ":",
        };
        var contentTypeStartsWith = "content-type" + separators.nameValue;
        let responseHeaders = aResponse.responseHeaders
            .split(separators.headers);
        let contentType = responseHeaders.find(function (aHeader) {
          return aHeader.toLowerCase().trim().startsWith(contentTypeStartsWith);
        });
        if (contentType) {
          contentType = contentType.split(separators.nameValue, 2);
          contentType = contentType[1] ? contentType[1].trim() : undefined;
        }
        let type = details.overrideMimeType || contentType
            || "application/octet-stream";
        let blob = new Blob([aResponse.response], {
          "type": type,
        });
        let url = URL.createObjectURL(blob);

        let a = document.createElement("a");
        a.setAttribute("href", url);
        a.setAttribute("download", details.name);
        a.setAttribute("style", "display: none;");
        document.documentElement.appendChild(a);
                
        let event = new MouseEvent("click");
        a.dispatchEvent(event);

        document.documentElement.removeChild(a);

        setTimeout(function () {
          URL.revokeObjectURL(url);
          blob = undefined;
        }, 1000);

        details.onload(aResponse);
      },
      "onprogress": function (aResponse) {
        details.onprogress(aResponse);
      },
      "ontimeout": function (aResponse) {
        details.ontimeout(aResponse);
      },
    };

    for (let i in details) {
      if (!(i in data)) {
        data[i] = details[i];
      }
    }

    try {
      return GM_xmlhttpRequest(data);
    } catch (e) {
      message = "\n" + "error: " + e.toString();
      message += "\n" + "url: " + details.url;
      message += "\n" + "name: " + details.name;
      message = _LOCALE.result.error.download.error
          .replace("%1", message);
      details.onerror({
        "details": message,
        "error": _RESULT.error.NOT_SUCCEEDED,
      });

      return false;
    }
  }
}