Tutorial on how to build a simple web server with node.js

Preface

Using Nodejs to build a web server is a comprehensive beginner tutorial for learning Node.js, because to complete a simple web server, you need to learn several important modules in Nodejs, such as: http protocol module, file system, url parsing module, path parsing module, and301Redirection issues, let's briefly explain how to set up a simple web server.

In the past, if you wanted to access local resources on the browser side without using a web server, you could use the Firefox browser, which can start a small web server by itself.
In order to make the code easy to understand for those who are just getting started with node, I will try to simplify the code in this article.

Prepare

First, you need to installnodejs，this can be downloaded from the official website, the current local installation is v0.12version.

After installation, you can test whether the installation is successful through the command line by entering: node -v, should display the current installed node version number.
The modules used in this article are all core modules of nodejs, which do not need to be downloaded from external sources. If necessary, you can use the following command to install: npm install xxx.

Start

Next, create a js file, which can be named server.js, the code is as follows:

var http = require('http');
 var url = require('url');
 var path = require('path');
 var fs = require('fs');
 var dir, arg = process.argv[2] || ''; // The third parameter of the command line is used to receive the directory, which can be empty, and the name of the directory relative to the server.js file
 // For example, use the command node server debug, which means the debug folder is at the same level as the server.js file
 // and you want to start the web service with the debug folder
 http.createServer(function (req, res) {
 var pathname = __dirname + url.parse(req.url).pathname;
 dir = dir ? dir : pathname; // Remember dir(directories)
 pathname = dir ? pathname.replace(dir, dir + arg + '/) : pathname; // Replace the static path of the file
 if (path.extname(pathname) == "") {
 pathname += "/";
 }
 if (pathname.charAt(pathname.length - 1) == "/)") {
 pathname += "index.html"; // Entry file, here index.html is the default
 }
 fs.exists(pathname, function (exists) {
 if (exists) {
 switch (path.extname(pathname)) {
 case ".html":
 res.writeHead(200, {"Content-Type": "text/html">);
 break;
 case ".js":
 res.writeHead(200, {"Content-Type": "text/javascript"});
 break;
 case ".css":
 res.writeHead(200, {"Content-Type": "text/css"});
 break;
 case ".gif":
 res.writeHead(200, {"Content-Type": "image/gif"});
 break;
 case ".jpg":
 res.writeHead(200, {"Content-Type": "image/jpeg"});
 break;
 case ".png":
 res.writeHead(200, {"Content-Type": "image/png"});
 break;
 default:
 res.writeHead(200, {"Content-Type": "application/octet-stream"});
 }
 // res can add information to interact simply, for example, you can modify some header information or modify the returned resource data
 fs.readFile(pathname, function (err, data) {
 res.end(data);
 });
 }
 else {
 res.writeHead(404, {"Content-Type": "text/html">);
 res.end("<h1>404 Not Found</h1>");
 }
 });
 }).listen(8085, "127.0.0.5"); // Server Port
 console.log("server running at http:",//127.0.0.5:8085/");

Start

After the node installation is complete and the above server.js file is also created, place it together with the folder you want to access, which can be placed at the same level or directly below. For example, if you want to access the d:\test\debug folder.

You can put the current file in the same level or directly below it, and then enter the following command to start the web service:

Firstly, open the `cmd` and enter the directory where the server file is located, such as the `test` directory;
Then enter: `node server debug` (same layer), or `node server` (sub-layer),
At this time, it will prompt `server running at http://127.0.0.5:8085/`, indicates that the service has started successfully;
Finally, open the browser and enter: `127.0.0.5:8085`, you can access this resource.

Finally

A simple explanation of the code above.

First, the most above require indicates which modules need to be used, let's reference them first;

arg indicates the third command line parameter entered, the above is manually intercepted;

The createServer method indicates creating an http service, taking a function as a parameter, an anonymous function is passed in in the code of this article;

req indicates the http request (request) object, which carries relevant information from the client's http request this time, such as request method, request query parameters, request header information, etc.;
res indicates the http response (return) object, used to return the requested resource to the client, can manually add information, such as returned data, returned headers, etc., and returned codes;
fs indicates the file resource object, you can visit the nodejs official website api for details;
path indicates the resource path object, you can visit the nodejs official website api for details.

listen indicates the service listener created, once accessed, it will enter the anonymous function callback before it, and return the resource to the client.

Summary

That's all for this article. I hope the content of this article can bring some help to everyone's learning or work. If you have any questions, you can leave messages for communication. Thank you for your support of the呐喊 tutorial.

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