Let’s briefly talk about streams in Node.js and talk about three ways to read files

This article will give you a brief understanding of the streams in Node.js, and introduce the three ways to read files: asynchronous reading of files, synchronous reading of files and streaming of reading files. .

Learn some basics of Node.js

1.fs module built-in module

npm i    第三方模块

Custom module written by myself (write js file). [Recommended learning: "nodejs Tutorial"]

2. Read the file

• Asynchronously read the file (readFile )

To solve the problem, use promise

• ##Read the file synchronously

  readFileSync

var nr = fs.readFileSync('./b.txt', 'utf-8')
console.log(nr)

• Read the file by stream

Read the video file and display the progress by percentage readVideo.js

Copy small files first read and then copy copyFile.js

• Write data
  ① Asynchronously write data

Copy big file

copybigFile.js

3. http Module

Method:

Create a service:

createServer((req,res)=>{
  // 设置一个响应头 ： 
  res.writeHead(200, {"Content-Type":"text/html;charset=utf-8"});
  req.url  // 获取客户端请求的网址  (除了 协议 端口 域名 之外的地址  http://www.baidu.com?main=22&pid=90)
  res.write(); // 响应用户的请求
  res.end(); // 结束响应
})
    get("url路径", 回调方法)  // 方法  请求服务器数据

• showPage.js

Exercise questions:

• ①

  ['1',',',',','2','3','9',',',','] Move the comma to the right

• ② There is an array with 1000 elements. The stored numbers are 1-999. One number is repeated. Please find it out.

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