nodejs basic application

1. The first nodejs application

n1_hello.js

console.log('hello word!');

Execute the file in the command line cmd (Open the command line at this file):

node n1_hello.js

Return the result from cmd on the command line:

hello word!

2. Basic format of nodejs

//步骤一：引入require模块，require指令载入http模块
var http = require('http');
//步骤二：创建服务器
http.createServer(function (request, response) {
 // 发送 HTTP 头部
 // HTTP 状态值: 200 : OK
 // 内容类型: text/html
 response.writeHead(200, {'Content-Type': 'text/html;chaset=utf-8;'});
//步骤三：接受请求与响应请求
 if(request.url!=='/favicon.ico'){
   ......
  // 发送响应数据
  response.end('');//必须有，没有则没有协议尾
 }
}).listen(8000);
// 终端打印如下信息
console.log('Server running at http://127.0.0.1:8000/');

3. Nodejs calling function

----------------- Call local function--------------------------------

var http = require('http');
http.createServer(function (request, response) {
 response.writeHead(200, {'Content-Type': 'text/html;chaset=utf-8;'});
 if(request.url!=='/favicon.ico'){
  fun1(response);
  // 发送响应数据
  response.end('');
 }
}).listen(8000);
// 终端打印如下信息
console.log('Server running at http://127.0.0.1:8000/');
function fun1(res){
 console.log('fun1');
 res.write('hello,我是fun1');
}

-----------------Call external functions-----------------------------

Note: External functions must be written in module.exports, exports is the interface exposed by the module

------------(1) Only call one function- ----------

In the main program:

var http = require('http');
var otherfun = require("./models/otherfuns.js");//调用外部页面的fun2
http.createServer(function (request, response) {
 response.writeHead(200, {'Content-Type': 'text/html;chaset=utf-8;'});
 if(request.url!=='/favicon.ico'){
  otherfun(response);//支持一个函数时
  response.end('');
 }
}).listen(8000);
// 终端打印如下信息
console.log('Server running at http://127.0.0.1:8000/');

otherfuns.js

function fun2(res){
 console.log('fun2');
 res.write('你好!,我是fun2');
}
module.exports = fun2;//只支持一个函数

------------(2) Call multiple functions-----------

Main program Medium:

var http = require('http');
var otherfun = require("./models/otherfuns.js");//调用写函数的外部页面otherfuns.js
http.createServer(function (request, response) {
 response.writeHead(200, {'Content-Type': 'text/html;chaset=utf-8;'});
 if(request.url!=='/favicon.ico'){
  //todo 以对象.方法名调用
  otherfun.fun2(response);
  otherfun.fun3(response);
  //todo 以字符串调用对应函数(结果同上)
  //otherfun['fun2'](response);
  //otherfun['fun3'](response);
  response.end('');
 }
}).listen(8000);
// 终端打印如下信息
console.log('Server running at http://127.0.0.1:8000/');
}

otherfuns.js Medium

module.exports={
 fun2:function(res){//匿名函数
  console.log('fun2');
  res.write('你好!,我是fun2');//在页面中输出
 },
 fun3:function(res){
  console.log('fun3');
  res.write('你好!,我是fun3');
 },
   ......
}

4. Preliminary nodejs routing

Main program n4_rout.js:

var http = require('http');
//引入url模块
var url = require('url');
http.createServer(function (request, response) {
 response.writeHead(200, {'Content-Type': 'text/html;chaset=utf-8;'});
 if(request.url!=='/favicon.ico'){
  var pathname = url.parse(request.url).pathname;
  pathname=pathname.replace(/\//,'');//替换掉前面的/
  console.log(pathname);
  response.end('');
 }
}).listen(8000);
// 终端打印如下信息
console.log('Server running at http://127.0.0.1:8000/');

Execute the file in the command line cmd, access: http://localhost:8000/, enter the routing address here, as shown below, and observe Command Line.

5. Nodejs reads files

Main program:

var http = require('http');
var optfile=require('./models/optfile');//导入文件
http.createServer(function (request, response) {
 // 发送 HTTP 头部
 // HTTP 状态值: 200 : OK
 // 内容类型: text/html
 response.writeHead(200, {'Content-Type': 'text/html;chaset=utf-8;'});
 if(request.url!=='/favicon.ico'){//清除第2次访问
  optfile.readfileSync('./views/login.html');//同步调用读取文件readfileSync()方法
  //optfile.readfile('./views/login.html',response);//异步步调用读取文件readfile（）方法
  response.end('ok!!!!!');//todo 不写没有协议尾
  console.log('主程序执行完毕！');
 }
}).listen(8000);
// 终端打印如下信息
console.log('Server running at http://127.0.0.1:8000/');

optfile In .js:

var fs=require('fs');//Node 导入文件系统模块(fs)语法 导入fs操作文件的类
module.exports={
 readfileSync:function(path){
  // 同步读取
  var data = fs.readFileSync(path,'utf-8');//以中文读取同步文件路径path
  console.log("同步方法执行完毕。");
 },
 readfile:function(path){
  // 异步读取
  fs.readFile(path,function (err, data) {
   if (err) {
    console.error(err);
   }else{
    console.log("异步读取: " + data.toString());
   }
  });
  console.log("异步方法执行完毕。");
 },
}

Result: In command line cmd

(1) When reading the file synchronously:

(2) When reading files asynchronously: (commonly used)

In the web page: all are:

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