node.js 利用流实现读写同步，边读边写

//10个数 10个字节，每次读4b,写1blet fs=require("fs");function pipe(source,target) { ???//先创建可读流，再创建可写流 ???//先读一次，rs.on(data) ???//将读到的类容写入目标中 ，返回布尔值，如果是ture,继续写，默认情况应该是false,暂停读取 ???//ws.on(‘drain‘),抽干后，回复读取 ???//监听读取文件完毕后，关闭读取rs.on(‘end‘) ???let rs=fs.createReadStream(source,{highWaterMark:4}); ???let ws=fs.createWriteStream(target,{highWaterMark:1}); ???rs.on(‘data‘,function (chunk) { ?//chunk是buffer类型 ???????if(ws.write(chunk)===false){ ???????????//写不下，停止读取 ???????????rs.pause() ???????} ???}); ???ws.on(‘drain‘,function () { ???????//每次写的内存干了就恢复读取 ???????console.log("111"); ???????rs.resume() //恢复读取 ???}); ???rs.on(‘end‘,function (chunk) { ???????ws.end(); ???})}pipe(‘./1.txt‘,‘./3.txt‘)

//10个数 10个字节，每次读4b,写1blet fs=require("fs");function pipe(source,target) { ???let rs=fs.createReadStream(source,{highWaterMark:4}); ???let ws=fs.createWriteStream(target,{highWaterMark:1}); ???//可读流到可写流,异步操作，可以保证内存不会被淹没，读一点，写一点 ???// 如果想看文件类容，使用readFile ???rs.pipe(ws);}pipe(‘./1.txt‘,‘./4.txt‘)