@fjedi/nodejs-file-downloader/utils/fileName.js

A file downloader for NodeJs

const sanitize = require("sanitize-filename");
const path = require("path");
var mime = require("mime-types");
const { promises: Fs } = require("fs");

/**
 *
 * @param {string} url
 * @return {string} fileName
 */
function deduceFileNameFromUrl(url) {
  const cleanUrl = removeQueryString(url);
  const baseName = sanitize(path.basename(cleanUrl));
  return baseName;
}

/**
 * Deduce the fileName, covering various scenarios.
 * @param {string} url
 * @param {Object} headers
 * @return {string} fileName
 */
function deduceFileName(url, headers) {
  // First option
  const fileNameFromContentDisposition = getFileNameFromContentDisposition(
    headers["content-disposition"] || headers["Content-Disposition"]
  );
  if (fileNameFromContentDisposition) return fileNameFromContentDisposition;

  //Second option
  if (path.extname(url)) {
    // First check if the url even has an extension
    const fileNameFromUrl = deduceFileNameFromUrl(url);
    if (fileNameFromUrl) return fileNameFromUrl;
  }

  // Third option
  const fileNameFromContentType = getFileNameFromContentType(
    headers["content-type"] || headers["Content-Type"],
    url
  );
  if (fileNameFromContentType) return fileNameFromContentType;

  // Fallback option
  return sanitize(url);
}

function removeQueryString(url) {
  return url.split(/[?#]/)[0];
}

function getFileNameFromContentType(contentType, url) {
  let extension = mime.extension(contentType);

  url = removeQueryString(url);
  const fileNameWithoutExtension = removeExtension(path.basename(url));
  return `${sanitize(fileNameWithoutExtension)}.${extension}`;
}

function getFileNameFromContentDisposition(contentDisposition) {
  if (!contentDisposition || !contentDisposition.includes("filename=")) {
    return "";
  }
  let filename = "";
  var filenameRegex = /filename[^;=\n]*=((['"]).*?\2|[^;\n]*)/;
  var matches = filenameRegex.exec(contentDisposition);
  if (matches != null && matches[1]) {
    filename = matches[1].replace(/['"]/g, "");
  }

  return filename ? sanitize(filename) : "";
}

function removeExtension(str) {
  const arr = str.split(".");
  if (arr.length == 1) {
    return str;
  }
  return arr.slice(0, -1).join(".");
}

async function exists(path) {
  try {
    await Fs.access(path);
    return true;
  } catch {
    return false;
  }
}

module.exports = { deduceFileName, exists };