node. JS Development----Message Board instance FS read-write file

The project structure is as follows:

App.js

CONST EXP = require (' Express '), Bodyparser = require (' Body-parser '), FS = require (' FS '), Multer = require ('            Multer '), APP = exp (), multipart = Multer (); The method used to create the object as above exp ()/multer ()//can be called Factory method App.use (exp.static (' static ')) App.use (bodyparser.urlencoded ()) App.post      ('/add ', Multipart.array (), (req, res) = {Console.log (Multipart.array ());           Content message Contents var = req.body.content//message is a JSON data format var message = {content:content,            Time:new Date (), ip:req.ip};              Asynchronously determines whether the file exists fs.exists (' data ', (exists) = {if (!exists) {///If the file does not exist, the file is created synchronously          The subsequent code fs.mkdirsync (' data ') will not continue until the file is created successfully.                  } fs.appendfile (' Data/message.txt ', json.stringify (message) + ', ', (error) = = {if (error) {       %s is called placeholder Console.error (' Error saving file:%s ', error '}   })})//file suffix determines what icon the operating system uses to display files//determine what program the operating system uses to open files//AppendFile can append data to the end of the file//if the file Does not exist, it automatically creates files//determines whether a file or folder exists Fs.exists//Create folder Fs.mkdir//delete file Fs.unlink//delete folder Fs.rmdir must is an empty folder to delete//Read file Fs.readfile res.status. JSON ({message: ' Thank you for your message! })//App.get ('/messages ', (req, res) = {fs.exists (' Data/message.txt ', (exists) + = {if (                      exists) {fs.readfile (' data/message.txt ', (error, data) = {if (!error) {                      var result = ' [' + data;                      result = Result.substr (0, result.length-1);                      result = result + '] ';                      Console.log (result);                  Res.status. Send (Result);          }})} else {res.status). Send (' [] '); })}) App.listen (+, () = Console.log (' Server RunninG.. '));   

　

Add.html

<! DOCTYPE html>  
　　
Index.js
var xhr = new XMLHttpRequest () Xhr.onreadystatechange = function () {if (xhr.readystate = = 4) {//Responset          Ext Response Text Console.log (xhr.responsetext);          var arr = json.parse (Xhr.responsetext);          Arr array Console.log (arr);          var messages = ';                            Reverse loop an array so that the latest message appears at the top for (var i = arr.length-1; i >-1; i--) {var message = Arr[i]; Use DOM to add message data to page//var box = document.createelement (' div ')//Document.body . appendchild (box)//var content = document.createelement (' P ')//Content.innertex t = message.content//box.appendchild (content)//var time = Document.createeleme                            NT (' span ')//Time.innertext = FormatDateTime (new Date (Message.time))//Box.appendchild (time)         var ip = document.createelement (' span ')     Ip.innertext = Formatip (MESSAGE.IP)//Box.appendchild (IP)//using a spelling string method to the page Add message messages + = ' <section> ' messages + = ' <p> ' Messages + = Message.cont ENT messages + = ' </p> ' messages + = ' <span> ' Messages + = FormatDateTime (              New Date (Message.time));              Messages + = ' </span> ' messages + = ' <span> ' Messages + formatip (MESSAGE.IP); Messages + = ' </span> ' messages + = ' </section> '} document.quer Yselector (' article '). InnerHTML = Messages}} xhr.open (' GET ', ' Messages ') Xhr.send () function FormatDateTime (                    T) {var m = t.getmonth () + 1, d = t.getdate (), H = t.gethours (), M = T.getminutes () JS is case-sensitive! So you can use M, m to represent two different variables m = m < 10? ' 0 ' + m:m d = d < 10? ' 0' + d:d H = h < 10? ' 0 ' + h:h m = m < 10? ' 0 ' + m:m return t.getfullyear () + '-' + M + '-' + D + ' + H + ': ' + m} function Formatip (IP) {if (Ip.startswith (':: 1 '))   {return ' 127.0.0.1 '} if (Ip.startswith (':: FFFF: ')} {return Ip.substr (7)}}
　
The final data is stored in JSON format in Message.txt


node. JS Development----Message Board instance FS read-write file