Node.js apis can be easily constructed in Express web framework.

Following example creates a simple GET api for listing all users.

Example

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

var users =[{
        id: 1,
        name: "John Doe",
        age : 23,
        email: "[email protected]"
    }];

// GET /api/users
app.get('/api/users', function(req, res){
    return res.json(users);    //return response as JSON
});

app.listen('3000', function(){
    console.log('Server listening on port 3000');
});

Following example create POST api using Express. This example is similar to GET example except the use of body-parser that parses the post data and add it to req.body.

Example

var express = require('express');
var app = express();
// for parsing the body in POST request
var bodyParser = require('body-parser');

var users =[{
    id: 1,
    name: "John Doe",
    age : 23,
    email: "[email protected]"
}];

app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());

// GET /api/users
app.get('/api/users', function(req, res){
    return res.json(users);    
});


/* POST /api/users
    {
        "user": {
           "id": 3,
            "name": "Test User",
            "age" : 20,
            "email": "[email protected]"
        }
    }
*/
app.post('/api/users', function (req, res) {
    var user = req.body.user;
    users.push(user);

    return res.send('User has been added successfully');
});

app.listen('3000', function(){
    console.log('Server listening on port 3000');
});