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： ```javascript 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： ```javascript 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); }; } ```