How to create REST API in Nodejs?

A REST API (Web API) is an application programming interface that allows us for interaction with RESTful web services or app services. REST stands for representational state transfer. It was created by computer scientist Roy Fielding. Here we will create REST API in Nodejs.

It uses HTTP requests to access and use data. The most common HTTP requests are GET, POST, PUT, DELETE.

REST API is useful in

Web Services
App Services
Cross Platform Applications
Cloud Applications
Stateless Applications
Communicate different devices or platforms

REST API supports the Data formats

application/json
application/xml
multipart/form-data
application/x-wbe+xml
application/x-www-form-urlencoded

Securing REST APIs

Using HTTPS
Blocking access from unknown IP addresses and domains
Validating Input and Output
Blocking unexpectedly large payloads
Logging requests
Investigating failures
Sending Status Codes like 200,400 etc
Validating Clients and Devices
Authorizing API
Authenticate URLs
Using Headers Authorization

Create REST API in Nodejs

Step1 : Create a folder database in root directory and create a file users.json. Paste the code given below.

{
	"user1" : {
		"id" : 1,
		"name" : "Chetan"
	}
}

Step 2 : Create a file api.js and paste the code given below.

var express = require("express");
var app = express();
var fs = require('fs');

/*get api*/

app.get('/list-users', function(req, res){
	fs.readFile(__dirname+'/database/users.json','utf8', function(err,data){
		res.end(data);
	});
});

/*post api*/
app.post('/create-user', function(req,res){

	fs.readFile(__dirname+'/database/users.json', 'utf8', function(err,data){
		data = JSON.parse(data);
		data["user2"] = {'id' : 2, "name": "Pankaj"};
		data = JSON.stringify(data);
		fs.writeFile(__dirname+'/database/users.json', data,function(res){
			console.log(res);
		});
		res.end(data);
	});

});

/*delete data*/

app.delete('/delete-user/:id', function(req, res){
	fs.readFile(__dirname+'/database/users.json', function(err,data){

		data = JSON.parse(data);
		
		delete data['user'+req.params.id];

		data = JSON.stringify(data);

		fs.writeFile(__dirname+'/database/users.json',data,function(res){
			console.log(res); //it is error response
		});

		res.end(data);

	});
});

/*create server*/

var server = app.listen(8081, function(){
	var host = server.address().address;
	var port = server.address().port;
	console.log('Server Running at http://%s:%s',host,port);
});

Step 3 : Install Express Node Package

Use these commands one by one

npm install express --save
npm install body-parser --save
npm install cookie-parser --save
npm install multer --save

Step 4 : Now run Node.js application
Use this command to run

node api.js

Step 5 : To test the api run the following URLs

http://localhost:8081/list-users

http://localhost:8081/create-user

http://localhost:8081/delete-user/1

You can replace localhost with your domain or IP

How to create REST API in Nodejs?

REST API is useful in

REST API supports the Data formats

Securing REST APIs

Create REST API in Nodejs

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