How to Create Secure (JWT) Token Based Authentication API with Node.js

Creating authentication REST API with Node Js is merely effortless. We will be taking the help of Express js to create the authentication endpoints and also make the MongoDB connection to store the user’s data in it.

Authentication Workflow with JSON Web Tokens

Let’s understand from the below diagram how does the secure authentication system work with JSON web token.

• A client makes the API call and sends the user information such as username and password to the webserver.
• On successful authentication a webserver generates a string-based token and returns to the client system.
• A client can store this token in the browser’s local storage or in a session.
• Client sets this token in a header something like “Bearer xxx.xxx.xxx”.
• On next API call JWT token communicateS with the server, and after the successful verification, the server returns the response to the client.

Initiate Node Token-Based Authentication Project

Create a project folder to build secure user authentication REST API, run the following command.

mkdir server

Get inside the project folder.

cd server

Let’s start the project by first creating the package.json file by running the following command.

npm init

Install NPM Packages to Create Secure Auth API

Next, install the NPM dependencies for the authentication API by running the given below command.

npm install express jsonwebtoken bcryptjs body-parser 
cors mongoose-unique-validator mongoose --save

Next, install the nodemon NPM module, it helps in starting the node server when any change occurs in the server files.

npm install nodemon --save-dev

Define Mongoose Schema

Next, we are going to define user schema using mongoose ODM. It allows us to retrieve the data from the database.

Create a folder and name it models inside the project directory, create a file User.js in it.

To prevent storing the duplicate email id in MongoDB database install mongoose-unique-validator package. Below we will learn how to use in mongoose schema to validate duplicate email id from MongoDB database.

npm i mongoose-unique-validator --save

Next, add the following code in models/User.js file:

// models/User.js

const mongoose = require('mongoose');
const Schema = mongoose.Schema;
const uniqueValidator = require('mongoose-unique-validator');

let userSchema = new Schema({
    name: {
        type: String
    },
    email: {
        type: String,
        unique: true
    },
    password: {
        type: String
    }
}, {
    collection: 'users'
})

userSchema.plugin(uniqueValidator, { message: 'Email already in use.' });
module.exports = mongoose.model('User', userSchema)

• The userSchema.plugin(uniqueValidator) method won’t let duplicate email id to be stored in the database.
• The unique: true property in email schema does the internal optimization to enhance the performance.

Implement MongoDB Database in Node App

Create database folder in the project folder and create a new file database/db.js in it.

module.exports = {
    db: 'mongodb://localhost:27017/meanauthdb'
}

Create Secure Token-based Authentication REST API in Node

To build secure user authentication endpoints in node, create routes folder, and auth.routes.js file in it.

Here, we will define CRUD Restful APIs using the npm packages for log-in, sign-up, update-user, and delete-user.

// routes/auth.routes.js

const express = require("express");
const jwt = require("jsonwebtoken");
const bcrypt = require("bcrypt");
const router = express.Router();
const userSchema = require("../models/User");

// Sign-up
router.post("/register-user", (req, res, next) => {
    bcrypt.hash(req.body.password, 10).then((hash) => {
        const user = new userSchema({
            name: req.body.name,
            email: req.body.email,
            password: hash
        });
        user.save().then((response) => {
            res.status(201).json({
                message: "User successfully created!",
                result: response
            });
        }).catch(error => {
            res.status(500).json({
                error: error
            });
        });
    });
});

// Sign-in
router.post("/signin", (req, res, next) => {
    let getUser;
    userSchema.findOne({
        email: req.body.email
    }).then(user => {
        if (!user) {
            return res.status(401).json({
                message: "Authentication failed"
            });
        }
        getUser = user;
        return bcrypt.compare(req.body.password, user.password);
    }).then(response => {
        if (!response) {
            return res.status(401).json({
                message: "Authentication failed"
            });
        }
        let jwtToken = jwt.sign({
            email: getUser.email,
            userId: getUser._id
        }, "longer-secret-is-better", {
            expiresIn: "1h"
        });
        res.status(200).json({
            token: jwtToken,
            expiresIn: 3600,
            msg: getUser
        });
    }).catch(err => {
        return res.status(401).json({
            message: "Authentication failed"
        });
    });
});

// Get Users
router.route('/').get((req, res) => {
    userSchema.find((error, response) => {
        if (error) {
            return next(error)
        } else {
            res.status(200).json(response)
        }
    })
})

// Get Single User
router.route('/user-profile/:id').get((req, res, next) => {
    userSchema.findById(req.params.id, (error, data) => {
        if (error) {
            return next(error);
        } else {
            res.status(200).json({
                msg: data
            })
        }
    })
})

// Update User
router.route('/update-user/:id').put((req, res, next) => {
    userSchema.findByIdAndUpdate(req.params.id, {
        $set: req.body
    }, (error, data) => {
        if (error) {
            return next(error);
            console.log(error)
        } else {
            res.json(data)
            console.log('User successfully updated!')
        }
    })
})

// Delete User
router.route('/delete-user/:id').delete((req, res, next) => {
    userSchema.findByIdAndRemove(req.params.id, (error, data) => {
        if (error) {
            return next(error);
        } else {
            res.status(200).json({
                msg: data
            })
        }
    })
})

module.exports = router;

• To secure the password, we are using the bcryptjs, It stores the hashed password in the database.
• In the signin API, we are checking whether the assigned and retrieved passwords are the same or not using the bcrypt.compare() method.
• In the signin API, we set the JWT token expiration time. Token will be expired within the defined duration.

Verify Node Authentication REST API

Next, we will verify the auth API using the JWT token. Create a middlewares folder and create a auth.js file inside of it, then include the following code in it.

Note: In the real world app the secret should not be kept in the code as declared below. The best practice is to store as an environment variable and it should be complex combination of numbers and strings.

// middlewares/auth.js

const jwt = require("jsonwebtoken");

module.exports = (req, res, next) => {
    try {
        const token = req.headers.authorization.split(" ")[1];
        jwt.verify(token, "longer-secret-is-better");
        next();
    } catch (error) {
        res.status(401).json({ message: "Authentication failed!" });
    }
};

Now, we will learn to implement JWT verification in the /user-profile endpoint. Import the following auth.js file from middlewares folder.

// Get User Profile
router.route('/user-profile/:id').get(authorize, (req, res, next) => {
    userSchema.findById(req.params.id, (error, data) => {
        if (error) {
            return next(error);
        } else {
            res.status(200).json({
                msg: data
            })
        }
    })
})

We added the authorize variable inside the user-profile API. It won’t render the data unless it has the valid JWT token. As you can see in the below screenshot, we have not defined the JWT token in get request, so we are getting the “No token provided” error.

Adding Input Validation in Express RESTful API

Next, we will learn to implement validation in Express auth API using POST body request. Install express-validator npm library to validate name, email and password.

The express-validator is an express.js middleware for validating POST body requests.

Run the below command to install the express-validator package.

npm install express-validator --save

Add the following code in the middlewares/auth.routes.js file.

// routes/auth.routes.js

const express = require("express");
const jwt = require("jsonwebtoken");
const bcrypt = require("bcrypt");
const router = express.Router();
const userSchema = require("../models/User");
const authorize = require("../middlewares/auth");
const { check, validationResult } = require('express-validator');

// Sign-up
router.post("/register-user",
    [
        check('name')
            .not()
            .isEmpty()
            .isLength({ min: 3 })
            .withMessage('Name must be atleast 3 characters long'),
        check('email', 'Email is required')
            .not()
            .isEmpty(),
        check('password', 'Password should be between 5 to 8 characters long')
            .not()
            .isEmpty()
            .isLength({ min: 5, max: 8 })
    ],
    (req, res, next) => {
        const errors = validationResult(req);
        console.log(req.body);

        if (!errors.isEmpty()) {
            return res.status(422).jsonp(errors.array());
        }
        else {
            bcrypt.hash(req.body.password, 10).then((hash) => {
                const user = new userSchema({
                    name: req.body.name,
                    email: req.body.email,
                    password: hash
                });
                user.save().then((response) => {
                    res.status(201).json({
                        message: "User successfully created!",
                        result: response
                    });
                }).catch(error => {
                    res.status(500).json({
                        error: error
                    });
                });
            });
        }
    });

// Sign-in
router.post("/signin", (req, res, next) => {
    let getUser;
    userSchema.findOne({
        email: req.body.email
    }).then(user => {
        if (!user) {
            return res.status(401).json({
                message: "Authentication failed"
            });
        }
        getUser = user;
        return bcrypt.compare(req.body.password, user.password);
    }).then(response => {
        if (!response) {
            return res.status(401).json({
                message: "Authentication failed"
            });
        }
        let jwtToken = jwt.sign({
            email: getUser.email,
            userId: getUser._id
        }, "longer-secret-is-better", {
            expiresIn: "1h"
        });
        res.status(200).json({
            token: jwtToken,
            expiresIn: 3600,
            _id: getUser._id
        });
    }).catch(err => {
        return res.status(401).json({
            message: "Authentication failed"
        });
    });
});

// Get Users
router.route('/').get((req, res) => {
    userSchema.find((error, response) => {
        if (error) {
            return next(error)
        } else {
            res.status(200).json(response)
        }
    })
})

// Get Single User
router.route('/user-profile/:id').get(authorize, (req, res, next) => {
    userSchema.findById(req.params.id, (error, data) => {
        if (error) {
            return next(error);
        } else {
            res.status(200).json({
                msg: data
            })
        }
    })
})

// Update User
router.route('/update-user/:id').put((req, res, next) => {
    userSchema.findByIdAndUpdate(req.params.id, {
        $set: req.body
    }, (error, data) => {
        if (error) {
            return next(error);
            console.log(error)
        } else {
            res.json(data)
            console.log('User successfully updated!')
        }
    })
})

// Delete User
router.route('/delete-user/:id').delete((req, res, next) => {
    userSchema.findByIdAndRemove(req.params.id, (error, data) => {
        if (error) {
            return next(error);
        } else {
            res.status(200).json({
                msg: data
            })
        }
    })
})

module.exports = router;

We Passed the validation array with the check() method inside the post() method as a second argument. Next, we called the validationResult() method to validate errors, and it returns the errors if found any.

Following validation we implemented in ("/register-user") api.

• Check if the value is required.
• Check min and max character’s length.

Final auth.routes.js

// routes/auth.routes.js

const express = require("express");
const jwt = require("jsonwebtoken");
const bcrypt = require("bcrypt");
const router = express.Router();
const userSchema = require("../models/User");
const authorize = require("../middlewares/auth");
const { check, validationResult } = require('express-validator');

// Sign-up
router.post("/register-user",
    [
        check('name')
            .not()
            .isEmpty()
            .isLength({ min: 3 })
            .withMessage('Name must be atleast 3 characters long'),
        check('email', 'Email is required')
            .not()
            .isEmpty(),
        check('password', 'Password should be between 5 to 8 characters long')
            .not()
            .isEmpty()
            .isLength({ min: 5, max: 8 })
    ],
    (req, res, next) => {
        const errors = validationResult(req);
        console.log(req.body);

        if (!errors.isEmpty()) {
            return res.status(422).jsonp(errors.array());
        }
        else {
            bcrypt.hash(req.body.password, 10).then((hash) => {
                const user = new userSchema({
                    name: req.body.name,
                    email: req.body.email,
                    password: hash
                });
                user.save().then((response) => {
                    res.status(201).json({
                        message: "User successfully created!",
                        result: response
                    });
                }).catch(error => {
                    res.status(500).json({
                        error: error
                    });
                });
            });
        }
    });

// Sign-in
router.post("/signin", (req, res, next) => {
    let getUser;
    userSchema.findOne({
        email: req.body.email
    }).then(user => {
        if (!user) {
            return res.status(401).json({
                message: "Authentication failed"
            });
        }
        getUser = user;
        return bcrypt.compare(req.body.password, user.password);
    }).then(response => {
        if (!response) {
            return res.status(401).json({
                message: "Authentication failed"
            });
        }
        let jwtToken = jwt.sign({
            email: getUser.email,
            userId: getUser._id
        }, "longer-secret-is-better", {
            expiresIn: "1h"
        });
        res.status(200).json({
            token: jwtToken,
            expiresIn: 3600,
            msg: getUser
        });
    }).catch(err => {
        return res.status(401).json({
            message: "Authentication failed"
        });
    });
});

// Get Users
router.route('/').get(authorize, (req, res) => {
    userSchema.find((error, response) => {
        if (error) {
            return next(error)
        } else {
            res.status(200).json(response)
        }
    })
})

// Get Single User
router.route('/user-profile/:id').get((req, res, next) => {
    userSchema.findById(req.params.id, (error, data) => {
        if (error) {
            return next(error);
        } else {
            res.status(200).json({
                msg: data
            })
        }
    })
})

// Update User
router.route('/update-user/:id').put((req, res, next) => {
    userSchema.findByIdAndUpdate(req.params.id, {
        $set: req.body
    }, (error, data) => {
        if (error) {
            return next(error);
            console.log(error)
        } else {
            res.json(data)
            console.log('User successfully updated!')
        }
    })
})

// Delete User
router.route('/delete-user/:id').delete((req, res, next) => {
    userSchema.findByIdAndRemove(req.params.id, (error, data) => {
        if (error) {
            return next(error);
        } else {
            res.status(200).json({
                msg: data
            })
        }
    })
})

module.exports = router;

Node Server Configuration

Create a server.js file in the token-based authentication project’s folder and paste the following code in it.

const express = require('express');
const mongoose = require('mongoose');
const cors = require('cors');
const bodyParser = require('body-parser');
const dbConfig = require('./database/db');

// Express APIs
const api = require('./routes/auth.routes');

// MongoDB conection
mongoose.Promise = global.Promise;
mongoose.connect(dbConfig.db, {
    useNewUrlParser: true,
    useUnifiedTopology: true
}).then(() => {
    console.log('Database connected')
},
    error => {
        console.log("Database can't be connected: " + error)
    }
)

// Remvoe MongoDB warning error
mongoose.set('useCreateIndex', true);

// Express settings
const app = express();
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: false
}));
app.use(cors());

// Serve static resources
app.use('/public', express.static('public'));

app.use('/api', api)

// Define PORT
const port = process.env.PORT || 4000;
const server = app.listen(port, () => {
    console.log('Connected to port ' + port)
})

// Express error handling
app.use((req, res, next) => {
    setImmediate(() => {
        next(new Error('Something went wrong'));
    });
});

app.use(function (err, req, res, next) {
    console.error(err.message);
    if (!err.statusCode) err.statusCode = 500;
    res.status(err.statusCode).send(err.message);
});

In this file we defined mongoDB database, express routes, PORT and errors.

Start Node Server

Now, we have placed everything at its place, and now it’s time to start the Node server. Open the terminal and run the given below commands to start the Node server and mongoDB:

Start the MongoDB database:

mongod

Start the nodemon server:

nodemon

You can test Node server on the following URL:
http://localhost:4000/api

Here, are the user authentication CRUD REST APIs built with Node.js.

API Methods	API URL
GET (Users List)	/api
POST (Sign in)	/api/signin
POST (Sign up)	/api/register-user
GET (User Profile)	/api/user-profile/id
PUT (Update User)	/api/update-user/id
DELETE (Delete User)	/api/delete-user/id

Conclusion

Finally, we have completed secure Token-Based Authentication REST API with Node.js tutorial. So far, In this tutorial we have learned how to securely store the password in the database using the hash method with bcryptjs, how to create JWT token to communicate with the client and a server using jsonwebtoken. We also implemented the Express input validation using the express-validator plugin.

I hope you liked this tutorial, please share it with others, thanks for reading!

#node.js #Express #MongoDB #JWT

What is GEEK

Buddha Community

How To Set Up Two-Factor Authentication in cPanel

What is 2FA
Two-Factor Authentication (or 2FA as it often referred to) is an extra layer of security that is used to provide users an additional level of protection when securing access to an account.
Employing a 2FA mechanism is a vast improvement in security over the Singe-Factor Authentication method of simply employing a username and password. Using this method, accounts that have 2FA enabled, require the user to enter a one-time passcode that is generated by an external application. The 2FA passcode (usually a six-digit number) is required to be input into the passcode field before access is granted. The 2FA input is usually required directly after the username and password are entered by the client.

#tutorials #2fa #access #account security #authentication #authentication method #authentication token #cli #command line #cpanel #feature manager #google authenticator #one time password #otp #otp authentication #passcode #password #passwords #qr code #security #security code #security policy #security practices #single factor authentication #time-based one-time password #totp #two factor authentication #whm

Top 10 API Security Threats Every API Team Should Know

As more and more data is exposed via APIs either as API-first companies or for the explosion of single page apps/JAMStack, API security can no longer be an afterthought. The hard part about APIs is that it provides direct access to large amounts of data while bypassing browser precautions. Instead of worrying about SQL injection and XSS issues, you should be concerned about the bad actor who was able to paginate through all your customer records and their data.

Typical prevention mechanisms like Captchas and browser fingerprinting won’t work since APIs by design need to handle a very large number of API accesses even by a single customer. So where do you start? The first thing is to put yourself in the shoes of a hacker and then instrument your APIs to detect and block common attacks along with unknown unknowns for zero-day exploits. Some of these are on the OWASP Security API list, but not all.

Insecure pagination and resource limits

Most APIs provide access to resources that are lists of entities such as /users or /widgets. A client such as a browser would typically filter and paginate through this list to limit the number items returned to a client like so:

First Call: GET /items?skip=0&take=10 
Second Call: GET /items?skip=10&take=10

However, if that entity has any PII or other information, then a hacker could scrape that endpoint to get a dump of all entities in your database. This could be most dangerous if those entities accidently exposed PII or other sensitive information, but could also be dangerous in providing competitors or others with adoption and usage stats for your business or provide scammers with a way to get large email lists. See how Venmo data was scraped

A naive protection mechanism would be to check the take count and throw an error if greater than 100 or 1000. The problem with this is two-fold:

1. For data APIs, legitimate customers may need to fetch and sync a large number of records such as via cron jobs. Artificially small pagination limits can force your API to be very chatty decreasing overall throughput. Max limits are to ensure memory and scalability requirements are met (and prevent certain DDoS attacks), not to guarantee security.
2. This offers zero protection to a hacker that writes a simple script that sleeps a random delay between repeated accesses.

skip = 0
while True:    response = requests.post('https://api.acmeinc.com/widgets?take=10&skip=' + skip),                      headers={'Authorization': 'Bearer' + ' ' + sys.argv[1]})    print("Fetched 10 items")    sleep(randint(100,1000))    skip += 10

How to secure against pagination attacks

To secure against pagination attacks, you should track how many items of a single resource are accessed within a certain time period for each user or API key rather than just at the request level. By tracking API resource access at the user level, you can block a user or API key once they hit a threshold such as “touched 1,000,000 items in a one hour period”. This is dependent on your API use case and can even be dependent on their subscription with you. Like a Captcha, this can slow down the speed that a hacker can exploit your API, like a Captcha if they have to create a new user account manually to create a new API key.

Insecure API key generation

Most APIs are protected by some sort of API key or JWT (JSON Web Token). This provides a natural way to track and protect your API as API security tools can detect abnormal API behavior and block access to an API key automatically. However, hackers will want to outsmart these mechanisms by generating and using a large pool of API keys from a large number of users just like a web hacker would use a large pool of IP addresses to circumvent DDoS protection.

How to secure against API key pools

The easiest way to secure against these types of attacks is by requiring a human to sign up for your service and generate API keys. Bot traffic can be prevented with things like Captcha and 2-Factor Authentication. Unless there is a legitimate business case, new users who sign up for your service should not have the ability to generate API keys programmatically. Instead, only trusted customers should have the ability to generate API keys programmatically. Go one step further and ensure any anomaly detection for abnormal behavior is done at the user and account level, not just for each API key.

Accidental key exposure

APIs are used in a way that increases the probability credentials are leaked:

1. APIs are expected to be accessed over indefinite time periods, which increases the probability that a hacker obtains a valid API key that’s not expired. You save that API key in a server environment variable and forget about it. This is a drastic contrast to a user logging into an interactive website where the session expires after a short duration.
2. The consumer of an API has direct access to the credentials such as when debugging via Postman or CURL. It only takes a single developer to accidently copy/pastes the CURL command containing the API key into a public forum like in GitHub Issues or Stack Overflow.
3. API keys are usually bearer tokens without requiring any other identifying information. APIs cannot leverage things like one-time use tokens or 2-factor authentication.

If a key is exposed due to user error, one may think you as the API provider has any blame. However, security is all about reducing surface area and risk. Treat your customer data as if it’s your own and help them by adding guards that prevent accidental key exposure.

How to prevent accidental key exposure

The easiest way to prevent key exposure is by leveraging two tokens rather than one. A refresh token is stored as an environment variable and can only be used to generate short lived access tokens. Unlike the refresh token, these short lived tokens can access the resources, but are time limited such as in hours or days.

The customer will store the refresh token with other API keys. Then your SDK will generate access tokens on SDK init or when the last access token expires. If a CURL command gets pasted into a GitHub issue, then a hacker would need to use it within hours reducing the attack vector (unless it was the actual refresh token which is low probability)

Exposure to DDoS attacks

APIs open up entirely new business models where customers can access your API platform programmatically. However, this can make DDoS protection tricky. Most DDoS protection is designed to absorb and reject a large number of requests from bad actors during DDoS attacks but still need to let the good ones through. This requires fingerprinting the HTTP requests to check against what looks like bot traffic. This is much harder for API products as all traffic looks like bot traffic and is not coming from a browser where things like cookies are present.

Stopping DDoS attacks

The magical part about APIs is almost every access requires an API Key. If a request doesn’t have an API key, you can automatically reject it which is lightweight on your servers (Ensure authentication is short circuited very early before later middleware like request JSON parsing). So then how do you handle authenticated requests? The easiest is to leverage rate limit counters for each API key such as to handle X requests per minute and reject those above the threshold with a 429 HTTP response. There are a variety of algorithms to do this such as leaky bucket and fixed window counters.

Incorrect server security

APIs are no different than web servers when it comes to good server hygiene. Data can be leaked due to misconfigured SSL certificate or allowing non-HTTPS traffic. For modern applications, there is very little reason to accept non-HTTPS requests, but a customer could mistakenly issue a non HTTP request from their application or CURL exposing the API key. APIs do not have the protection of a browser so things like HSTS or redirect to HTTPS offer no protection.

How to ensure proper SSL

Test your SSL implementation over at Qualys SSL Test or similar tool. You should also block all non-HTTP requests which can be done within your load balancer. You should also remove any HTTP headers scrub any error messages that leak implementation details. If your API is used only by your own apps or can only be accessed server-side, then review Authoritative guide to Cross-Origin Resource Sharing for REST APIs

Incorrect caching headers

APIs provide access to dynamic data that’s scoped to each API key. Any caching implementation should have the ability to scope to an API key to prevent cross-pollution. Even if you don’t cache anything in your infrastructure, you could expose your customers to security holes. If a customer with a proxy server was using multiple API keys such as one for development and one for production, then they could see cross-pollinated data.

#api management #api security #api best practices #api providers #security analytics #api management policies #api access tokens #api access #api security risks #api access keys

NBB: Ad-hoc CLJS Scripting on Node.js

Nbb

Not babashka. Node.js babashka!?

Ad-hoc CLJS scripting on Node.js.

Status

Experimental. Please report issues here.

Goals and features

Nbb's main goal is to make it easy to get started with ad hoc CLJS scripting on Node.js.

Additional goals and features are:

• Fast startup without relying on a custom version of Node.js.
• Small artifact (current size is around 1.2MB).
• First class macros.
• Support building small TUI apps using Reagent.
• Complement babashka with libraries from the Node.js ecosystem.

Requirements

Nbb requires Node.js v12 or newer.

How does this tool work?

CLJS code is evaluated through SCI, the same interpreter that powers babashka. Because SCI works with advanced compilation, the bundle size, especially when combined with other dependencies, is smaller than what you get with self-hosted CLJS. That makes startup faster. The trade-off is that execution is less performant and that only a subset of CLJS is available (e.g. no deftype, yet).

Usage

Install nbb from NPM:

$ npm install nbb -g

Omit -g for a local install.

Try out an expression:

$ nbb -e '(+ 1 2 3)'
6

And then install some other NPM libraries to use in the script. E.g.:

$ npm install csv-parse shelljs zx

Create a script which uses the NPM libraries:

(ns script
  (:require ["csv-parse/lib/sync$default" :as csv-parse]
            ["fs" :as fs]
            ["path" :as path]
            ["shelljs$default" :as sh]
            ["term-size$default" :as term-size]
            ["zx$default" :as zx]
            ["zx$fs" :as zxfs]
            [nbb.core :refer [*file*]]))

(prn (path/resolve "."))

(prn (term-size))

(println (count (str (fs/readFileSync *file*))))

(prn (sh/ls "."))

(prn (csv-parse "foo,bar"))

(prn (zxfs/existsSync *file*))

(zx/$ #js ["ls"])

Call the script:

$ nbb script.cljs
"/private/tmp/test-script"
#js {:columns 216, :rows 47}
510
#js ["node_modules" "package-lock.json" "package.json" "script.cljs"]
#js [#js ["foo" "bar"]]
true
$ ls
node_modules
package-lock.json
package.json
script.cljs

Macros

Nbb has first class support for macros: you can define them right inside your .cljs file, like you are used to from JVM Clojure. Consider the plet macro to make working with promises more palatable:

(defmacro plet
  [bindings & body]
  (let [binding-pairs (reverse (partition 2 bindings))
        body (cons 'do body)]
    (reduce (fn [body [sym expr]]
              (let [expr (list '.resolve 'js/Promise expr)]
                (list '.then expr (list 'clojure.core/fn (vector sym)
                                        body))))
            body
            binding-pairs)))

Using this macro we can look async code more like sync code. Consider this puppeteer example:

(-> (.launch puppeteer)
      (.then (fn [browser]
               (-> (.newPage browser)
                   (.then (fn [page]
                            (-> (.goto page "https://clojure.org")
                                (.then #(.screenshot page #js{:path "screenshot.png"}))
                                (.catch #(js/console.log %))
                                (.then #(.close browser)))))))))

Using plet this becomes:

(plet [browser (.launch puppeteer)
       page (.newPage browser)
       _ (.goto page "https://clojure.org")
       _ (-> (.screenshot page #js{:path "screenshot.png"})
             (.catch #(js/console.log %)))]
      (.close browser))

See the puppeteer example for the full code.

Since v0.0.36, nbb includes promesa which is a library to deal with promises. The above plet macro is similar to promesa.core/let.

Startup time

$ time nbb -e '(+ 1 2 3)'
6
nbb -e '(+ 1 2 3)'   0.17s  user 0.02s system 109% cpu 0.168 total

The baseline startup time for a script is about 170ms seconds on my laptop. When invoked via npx this adds another 300ms or so, so for faster startup, either use a globally installed nbb or use $(npm bin)/nbb script.cljs to bypass npx.

Dependencies

NPM dependencies

Nbb does not depend on any NPM dependencies. All NPM libraries loaded by a script are resolved relative to that script. When using the Reagent module, React is resolved in the same way as any other NPM library.

Classpath

To load .cljs files from local paths or dependencies, you can use the --classpath argument. The current dir is added to the classpath automatically. So if there is a file foo/bar.cljs relative to your current dir, then you can load it via (:require [foo.bar :as fb]). Note that nbb uses the same naming conventions for namespaces and directories as other Clojure tools: foo-bar in the namespace name becomes foo_bar in the directory name.

To load dependencies from the Clojure ecosystem, you can use the Clojure CLI or babashka to download them and produce a classpath:

$ classpath="$(clojure -A:nbb -Spath -Sdeps '{:aliases {:nbb {:replace-deps {com.github.seancorfield/honeysql {:git/tag "v2.0.0-rc5" :git/sha "01c3a55"}}}}}')"

and then feed it to the --classpath argument:

$ nbb --classpath "$classpath" -e "(require '[honey.sql :as sql]) (sql/format {:select :foo :from :bar :where [:= :baz 2]})"
["SELECT foo FROM bar WHERE baz = ?" 2]

Currently nbb only reads from directories, not jar files, so you are encouraged to use git libs. Support for .jar files will be added later.

Current file

The name of the file that is currently being executed is available via nbb.core/*file* or on the metadata of vars:

(ns foo
  (:require [nbb.core :refer [*file*]]))

(prn *file*) ;; "/private/tmp/foo.cljs"

(defn f [])
(prn (:file (meta #'f))) ;; "/private/tmp/foo.cljs"

Reagent

Nbb includes reagent.core which will be lazily loaded when required. You can use this together with ink to create a TUI application:

$ npm install ink

ink-demo.cljs:

(ns ink-demo
  (:require ["ink" :refer [render Text]]
            [reagent.core :as r]))

(defonce state (r/atom 0))

(doseq [n (range 1 11)]
  (js/setTimeout #(swap! state inc) (* n 500)))

(defn hello []
  [:> Text {:color "green"} "Hello, world! " @state])

(render (r/as-element [hello]))

Promesa

Working with callbacks and promises can become tedious. Since nbb v0.0.36 the promesa.core namespace is included with the let and do! macros. An example:

(ns prom
  (:require [promesa.core :as p]))

(defn sleep [ms]
  (js/Promise.
   (fn [resolve _]
     (js/setTimeout resolve ms))))

(defn do-stuff
  []
  (p/do!
   (println "Doing stuff which takes a while")
   (sleep 1000)
   1))

(p/let [a (do-stuff)
        b (inc a)
        c (do-stuff)
        d (+ b c)]
  (prn d))

$ nbb prom.cljs
Doing stuff which takes a while
Doing stuff which takes a while
3

Also see API docs.

Js-interop

Since nbb v0.0.75 applied-science/js-interop is available:

(ns example
  (:require [applied-science.js-interop :as j]))

(def o (j/lit {:a 1 :b 2 :c {:d 1}}))

(prn (j/select-keys o [:a :b])) ;; #js {:a 1, :b 2}
(prn (j/get-in o [:c :d])) ;; 1

Most of this library is supported in nbb, except the following:

• destructuring using :syms
• property access using .-x notation. In nbb, you must use keywords.

See the example of what is currently supported.

Examples

See the examples directory for small examples.

Also check out these projects built with nbb:

• c64core: retrocompute aesthetics twitter bot
• gallery.cljs: script to download walpapers from windowsonearth.org.
• nbb-action-example: example of a Github action built with nbb.

API

See API documentation.

Migrating to shadow-cljs

See this gist on how to convert an nbb script or project to shadow-cljs.

Build

Prequisites:

• babashka >= 0.4.0
• Clojure CLI >= 1.10.3.933
• Node.js 16.5.0 (lower version may work, but this is the one I used to build)

To build:

• Clone and cd into this repo
• bb release

Run bb tasks for more project-related tasks.

Download Details:
Author: borkdude
Download Link: Download The Source Code
Official Website: https://github.com/borkdude/nbb 
License: EPL-1.0

#node #javascript

Hire Dedicated Node.js Developers - Hire Node.js Developers

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Why use Node.js for Web Development? Benefits and Examples of Apps

Front-end web development has been overwhelmed by JavaScript highlights for quite a long time. Google, Facebook, Wikipedia, and most of all online pages use JS for customer side activities. As of late, it additionally made a shift to cross-platform mobile development as a main technology in React Native, Nativescript, Apache Cordova, and other crossover devices. 

Throughout the most recent couple of years, Node.js moved to backend development as well. Designers need to utilize a similar tech stack for the whole web project without learning another language for server-side development. Node.js is a device that adjusts JS usefulness and syntax to the backend. 

What is Node.js? 

Node.js isn’t a language, or library, or system. It’s a runtime situation: commonly JavaScript needs a program to work, however Node.js makes appropriate settings for JS to run outside of the program. It’s based on a JavaScript V8 motor that can run in Chrome, different programs, or independently. 

The extent of V8 is to change JS program situated code into machine code — so JS turns into a broadly useful language and can be perceived by servers. This is one of the advantages of utilizing Node.js in web application development: it expands the usefulness of JavaScript, permitting designers to coordinate the language with APIs, different languages, and outside libraries.

What Are the Advantages of Node.js Web Application Development? 

Of late, organizations have been effectively changing from their backend tech stacks to Node.js. LinkedIn picked Node.js over Ruby on Rails since it took care of expanding responsibility better and decreased the quantity of servers by multiple times. PayPal and Netflix did something comparative, just they had a goal to change their design to microservices. We should investigate the motivations to pick Node.JS for web application development and when we are planning to hire node js developers. 

Amazing Tech Stack for Web Development 

The principal thing that makes Node.js a go-to environment for web development is its JavaScript legacy. It’s the most well known language right now with a great many free devices and a functioning local area. Node.js, because of its association with JS, immediately rose in ubiquity — presently it has in excess of 368 million downloads and a great many free tools in the bundle module. 

Alongside prevalence, Node.js additionally acquired the fundamental JS benefits: 

• quick execution and information preparing; 
• exceptionally reusable code; 
• the code is not difficult to learn, compose, read, and keep up; 
• tremendous asset library, a huge number of free aides, and a functioning local area. 

In addition, it’s a piece of a well known MEAN tech stack (the blend of MongoDB, Express.js, Angular, and Node.js — four tools that handle all vital parts of web application development). 

Designers Can Utilize JavaScript for the Whole Undertaking 

This is perhaps the most clear advantage of Node.js web application development. JavaScript is an unquestionable requirement for web development. Regardless of whether you construct a multi-page or single-page application, you need to know JS well. On the off chance that you are now OK with JavaScript, learning Node.js won’t be an issue. Grammar, fundamental usefulness, primary standards — every one of these things are comparable. 

In the event that you have JS designers in your group, it will be simpler for them to learn JS-based Node than a totally new dialect. What’s more, the front-end and back-end codebase will be basically the same, simple to peruse, and keep up — in light of the fact that they are both JS-based. 

A Quick Environment for Microservice Development 

There’s another motivation behind why Node.js got famous so rapidly. The environment suits well the idea of microservice development (spilling stone monument usefulness into handfuls or many more modest administrations). 

Microservices need to speak with one another rapidly — and Node.js is probably the quickest device in information handling. Among the fundamental Node.js benefits for programming development are its non-obstructing algorithms.

Node.js measures a few demands all at once without trusting that the first will be concluded. Many microservices can send messages to one another, and they will be gotten and addressed all the while. 

Versatile Web Application Development 

Node.js was worked in view of adaptability — its name really says it. The environment permits numerous hubs to run all the while and speak with one another. Here’s the reason Node.js adaptability is better than other web backend development arrangements. 

Node.js has a module that is liable for load adjusting for each running CPU center. This is one of numerous Node.js module benefits: you can run various hubs all at once, and the environment will naturally adjust the responsibility. 

Node.js permits even apportioning: you can part your application into various situations. You show various forms of the application to different clients, in light of their age, interests, area, language, and so on. This builds personalization and diminishes responsibility. Hub accomplishes this with kid measures — tasks that rapidly speak with one another and share a similar root. 

What’s more, Node’s non-hindering solicitation handling framework adds to fast, letting applications measure a great many solicitations. 

Control Stream Highlights

Numerous designers consider nonconcurrent to be one of the two impediments and benefits of Node.js web application development. In Node, at whatever point the capacity is executed, the code consequently sends a callback. As the quantity of capacities develops, so does the number of callbacks — and you end up in a circumstance known as the callback damnation. 

In any case, Node.js offers an exit plan. You can utilize systems that will plan capacities and sort through callbacks. Systems will associate comparable capacities consequently — so you can track down an essential component via search or in an envelope. At that point, there’s no compelling reason to look through callbacks.

 

Final Words

So, these are some of the top benefits of Nodejs in web application development. This is how Nodejs is contributing a lot to the field of web application development. 

I hope now you are totally aware of the whole process of how Nodejs is really important for your web project. If you are looking to hire a node js development company in India then I would suggest that you take a little consultancy too whenever you call. 

Good Luck!

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