for (var i=0;i<dataArray.length;i++) { var timenow=Date.now();//调用的时候，打个时间戳 const options = { directory: downloadPath, filename: dataArray[i].title + '.' + dataArray[i].fileType, saveAs: false, extension: dataArray[i].fileType, openFolderWhenDone: false, showProgressBar: true, showBadge: true, }; var downloader = new Downloader(dataArray[i], options); downloader.data.timeid=timenow;//存储唯一标识 downloader.start(); downloader.onStart = () => { // 下载开始 handleDownload.push(downloader); mainWindow.webContents.send('consolelog2', '检查代码在此执行次数'); }; downloader.onTotalProgress = (progress) => { // 更新下载进度 downloadArray.set(downloader.data.timeid, { title: downloader.data.title, sUrl: downloader.data.sUrl, progress: downloader.data.progress, size: downloader.data.size, status:downloader.data.status, timeid:downloader.data.timeid }); mainWindow.webContents.send('consolelog', downloadArray); mainWindow.webContents.send('donwloadStatus', true); }; downloader.onCompleted = () => { if(downloader.data.progress==100&&downloader.data.status=='process'){ mainWindow.webContents.send('endDownload', JSON.stringify(downloader)); mainWindow.webContents.send('donwloadStatus', false); downloader.data.status='complete' } if(downloader.data.progress<100){ mainWindow.webContents.send('donwloadStatus', true); } mainWindow.webContents.send('consolelog', downloadArray); }; } return JSON.stringify(dataArray); // 返回值将作为 Promise 的 resolved 值 }); 这段代码中，如果我是多个下载器，var downloader = new Downloader(dataArray[i], options); 这里就会导致重复创建一个名字的下载，导致我操作 downloader.start(); 的时候，会触发多个下载器的 start ，我要怎么优化。把下载器分离出独立

可以将 Downloader 类提取出来，单独作为一个模块，然后在循环中实例化多个 Downloader 对象，这样就可以避免重复创建相同名字的下载器。示例代码如下：

1. 创建 Downloader 类的模块 downloader.js：

const request = require('request');
const fs = require('fs');
const path = require('path');

class Downloader {
  constructor(data, options) {
    this.data = data;
    this.options = options;
    this.req = null; // request 对象
    this.writeStream = null; // 文件写入流
  }

  start() {
    const { sUrl } = this.data;
    const { directory, filename, saveAs, extension } = this.options;
    const filePath = path.join(directory, saveAs ? filename : `${Date.now()}.${extension}`);

    this.writeStream = fs.createWriteStream(filePath);
    this.req = request
      .get(sUrl)
      .on('error', (err) => {
        console.error(`请求 ${sUrl} 出错：${err.message}`);
        this.data.status = 'failed';
      })
      .on('response', (response) => {
        if (response.statusCode === 200) {
          this.data.size = parseInt(response.headers['content-length'], 10);
        } else {
          this.data.status = 'failed';
        }
      })
      .on('data', (chunk) => {
        this.writeStream.write(chunk);
        this.data.progress = (this.writeStream.bytesWritten / this.data.size) * 100;
      })
      .on('end', () => {
        this.writeStream.end();
        this.data.progress = 100;
        this.data.status = 'complete';
      });
  }

  pause() {
    if (this.req) {
      this.req.pause();
    }
    if (this.writeStream) {
      this.writeStream.close();
    }
  }

  resume() {
    this.start();
  }

  cancel() {
    this.pause();
    const { directory, saveAs, extension } = this.options;
    const filePath = path.join(directory, saveAs ? this.data.filename : `${Date.now()}.${extension}`);
    fs.unlink(filePath, (err) => {
      if (err) {
        console.error(`删除文件 ${filePath} 出错：${err.message}`);
      }
    });
  }
}

module.exports = Downloader;

2. 修改原来的代码，引入 downloader.js 模块，并实例化多个 Downloader 对象：

const Downloader = require('./downloader');

...

for (let i = 0; i < dataArray.length; i++) {
  const timenow = Date.now();
  const options = {
    directory: downloadPath,
    filename: dataArray[i].title + '.' + dataArray[i].fileType,
    saveAs: false,
    extension: dataArray[i].fileType,
    openFolderWhenDone: false,
    showProgressBar: true,
    showBadge: true,
  };
  const downloader = new Downloader(dataArray[i], options);
  downloader.data.timeid = timenow;
  downloader.start();
  handleDownload.push(downloader);
  downloader.onTotalProgress = (progress) => {
    downloadArray.set(downloader.data.timeid, {
      title: downloader.data.title,
      sUrl: downloader.data.sUrl,
      progress: downloader.data.progress,
      size: downloader.data.size,
      status: downloader.data.status,
      timeid: downloader.data.timeid
    });
    mainWindow.webContents.send('consolelog', downloadArray);
    mainWindow.webContents.send('donwloadStatus', true);
  };
  downloader.onCompleted = () => {
    if (downloader.data.progress === 100 && downloader.data.status === 'process') {
      mainWindow.webContents.send('endDownload', JSON.stringify(downloader));
      mainWindow.webContents.send('donwloadStatus', false);
      downloader.data.status = 'complete';
    }
    if (downloader.data.progress < 100) {
      mainWindow.webContents.send('donwloadStatus', true);
    }
    mainWindow.webContents.send('consolelog', downloadArray);
  };
}