Nodejs (02) - built in module

• os Operating system modules
• path Path module
• url modular
• fs File module
• Simulate server

This article only aims at window operating system
This article only records a few commonly used attributes 、 Some modules , Not all practice
details API Please refer to the document :http://nodejs.cn/api/os.html

os Operating system modules

grammar

var os=require("os");

Method

Method name	Detailed explanation
EOL	Line break
hostname()	Host name
type()	System
totalmem()	Memory
cpus()	be-all cpu

Example

var os=require("os");
console.log('hello'+os.EOL+"nodejs");// Line break 
console.log(' Host name '+os.hostname());
console.log(" System "+os.type());
console.log(" Memory :"+os.totalmem());
console.log(os.cpus());

path Path module

grammar

var path=require("path");

Method

Method name	Detailed explanation
basename( File path )	file name
dirname( File path )	Folder name
extname( File path )	File suffix
format( object )	Splicing path for example :dir: Folder path base: file name
parse( File path )	Split path ( And format contrary )

Example

/*  Path module  */
var path=require('path');
var testfile='D:\\pk\\dconfig.json';
var name=path.basename(testfile);// file name 
var dname=path.dirname(testfile);// Folder name 
var extname=path.extname(testfile);// Suffix name 
let ok=path.format({
    
    dir:'c:\\images\\users',
    base:'bg1.jpg'
});// Splicing path 
let parse=path.parse('c:\\images\\users\\bg1.jpg');// And format contrary 

console.log(" file name "+name+" Folder name :"+dname+" suffix :"+extname);
console.log(" Splicing path :"+ok);
console.log(" Split path :",parse);

url modular

grammar

const url=new URL('https://example.org/abc?123#find');

attribute

Property name	Detailed explanation
href	URL path
host	Website host part
pathname	Parameter name
search	Parameter values
hash	Set get fragment part #

Example

/** * url modular  */
const url=new URL('https://example.org/abc?123#find');
console.log(url.hash);// Get the segment 
// Set the segment 
url.hash="sethash";
console.log(url.href);// The modified website 
console.log(url.host);// Website host part 
console.log(url.pathname);
console.log(url.search);

fs File read and write

grammar

var fs=require('fs');

Reading documents

Create a data.txt The contents of the document :

hello filesystem
CSDN---> Bump 

// read 
fs.readFile('day1/data.txt',(err,data)=>{
    
    if(err){
    
        console.log(" Read failed ");
        return;
    }
    //data Is the data read 
    // console.log(data);// binary data 
    console.log(data.toString());
})

Writing documents

const data='Hello  Bump !';
fs.writeFile('day1/pengke.txt',data,(error)=>{
    
    if(error){
    
        console.log(" Failed to write file ");
        return;
    }
    console.log(" Write successfully !!!");
})

Finally get a file pengke.txt

Hello  Bump !

Simulate server (http)

Key modules ：http

Example

/** *  Simulate server  */
var http=require("http");
var port=1234;// Port number 
var server=http.createServer((req,resp)=>{
    
    // Get browser request 
    console.log(" Get request :",req.url);
    if(req.url=='/'){
    
        $msg=' This is the home page ';
    }else if(req.url=='/login'){
    
        $msg=' Here is the landing page ';
    }else{
    
        $msg='404';
    }
    // The response data 
    resp.writeHead(200,{
    'Content-Type':'text/html;charset=utf-8'});
    resp.write($msg);
    resp.end();
});
server.listen(port);
console.log(" The server is running ....http://127.0.0.1:"+port);

practice (fs+http)

By modifying the http Path to write content to txt And get it and display it on the page

/** *  Simulate server  */
var http=require("http");
const fs=require("fs");
var port=1234;// Port number 
var server=http.createServer((req,resp)=>{
    
    var data=' This is the home page ';
    // Get browser request 
    console.log(" Get request :",req.url);
    if(req.url=='/'){
    
        console.log("index");
        data=' This is the home page ';
    }else if(req.url=='/login'){
    
        console.log("login");
        data=' Here is the landing page ';
    }else{
    
        console.log("404");
        data='404';
    }
    fs.writeFile('day1/pengke.txt',data,(error)=>{
    
        console.log("data="+data);
        if(error){
    
            console.log(" Failed to write file ");
            return;
        }
        console.log(" Write successfully !!!");
    })
    fs.readFile('day1/pengke.txt','utf-8',(err,datas)=>{
    
        if(err){
    
            console.log(" Read failed ");
            return;
        }
        // The response data 
    resp.writeHead(200,{
    'Content-Type':'text/html;charset=utf-8'});
    resp.write(datas);
    // resp.end();
    })
    
    

});
server.listen(port);

console.log(" The server is running ....http://127.0.0.1:"+port);

The practice of the built-in module is over .