lib.js

const path = require("path");
const url = require("url");
const request = require("request-promise-native");
const imageType = require("image-type");
const shortid = require("shortid");
const fs = require("fs");

exports.equativePath = (filePath, relativePath = "") => {
  return path.resolve(filePath, "..", relativePath);
};
exports.checkRelative = link => require("is-relative-url")(link); //|| require("is-relative")(link);
exports.checkValid = link =>
  require("valid-url").isUri(link) || require("valid-path")(link);
exports.downloader = async function(imgUrl, downloadPath, options = {}) {
  // 图片名处理
  const urlPathname = url.parse(imgUrl).pathname,
    hasExtName = path.extname(urlPathname);
  let basename = path.basename(urlPathname);
  // 是否覆盖同名图片（对无后缀图片暂时无解）
  // todo: 把这段代码转移到外面的pMap上面去
  // todo: 明明extract图片链接的时候已经把相对和已存在图片滤掉了，为啥还会显示在命令行
  if (
    !options.cover &&
    hasExtName &&
    fs.existsSync(path.join(downloadPath, basename))
  )
    return;

  const res = await request({
    method: "GET",
    uri: imgUrl,
    resolveWithFullResponse: true,
    encoding: null // 返回binary格式数据
  });

  if (res.body && (res.statusCode === 200 || res.statusCode === 201)) {
    // 如果url没有文件后缀名，则加上后缀
    if (!hasExtName) basename = basename + "." + imageType(res.body).ext;
    // 如果存在同名图片，则改名
    if (fs.existsSync(path.join(downloadPath, basename)))
      basename = shortid.generate() + "-" + basename;

    fs.writeFileSync(
      path.join(downloadPath, basename),
      res.body,
      "binary",
      err => {
        if (err) {
          throw new Error(`图片写入失败. URL: ${imgUrl}`);
        }
        // if (typeof done === "function") {
        //     done(false, options.dest, res.body);
        // }
      }
    );

    return basename;
  } else {
    if (!res.body) {
      throw new Error(`图片下载失败，empty body. URL: ${imgUrl}`);
    }
    throw new Error(`图片下载失败，${res.statusCode}. URL: ${imgUrl}`);
  }
};