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State management is a core capability of React which allows us to share data across component re-renders. This capability was reserved for class components, while the functional components were only used for presentational purposes. However, it was after the introduction of React hooks that state management became possible in functional components. The ironic part is that this new way of state management became so popular among the developers rendering the class components redundant.

Hooks were released in React version 16.8 in February 2019. React framework has been around since 29 May 2019. For 6 years React has powered many web applications and state management via class components remained the de facto standard. So, the real question is, If State management was already possible, 

what was the motivation behind the invention of hooks? 

To answer this question let's look at some of the major benefits react hooks offers.

 Using hooks with functional components makes the code simpler and shorter. Class components introduce their own concepts such as this keyword, function bindings, constructors, super functions, etc. We don't have to deal with these complexities with functional components.

 Hooks allow us to improve usability by encapsulating a shared logic by implementing a custom hook and using it across components.

 React Hooks make the code easier to read and debug. For E.g. in class components, we have to deal with 

 keyword and method bindings which increase complexity. In functional components, we don't have to deal with them.

Now we are going to explore some of the most commonly used React hooks.

 hook lets us add state to a functional component. It takes an optional argument as an initial state and returns an array of 2 values i.e. the current state and the state modifier function.

The initial value if provided becomes the current state for the first render. For further updating the state we use the state modifier function returned by the 

 hook. Whenever the state is updated, React re-renders the component with the latest state data, hence, maintaining the latest data on the UI. E.g -

  // use state hook with initial argument and returned array

      <button onClick={handleIncrement}>Increment</button>

 hook is used to manage side effects in functional components. In class components, we use lifecycle methods for it. Side effects are the actions performed outside the scope of the component such as fetching data from an external source, performing actions in a setTimeout function, or updating closure-scoped variables

useEffect hook takes 1 mandatory argument i.e. a function that performs side effects and an optional argument i.e. an array of dependencies. If the arguments array is not given it performs side effects every time the component renders, otherwise, it performs side effects only if there is a change in the dependencies. E.g -

import React, { useState, useEffect } from 'react';

        const response = await axios.get('https://jsonplaceholder.typicode.com/posts');

    console.log("I run on every render");

          <li key={item.id}>{item.title}</li>

In the above example, we have used axios library to fetch data from an API and store it in a state variable. The UI then re-renders to display the latest data. The empty dependency array 

 indicates that there are no dependencies, therefore, the side effect will happen only once and not on every render. The second 

 will execute on every render because the dependency array is not provided. We can also have more than one 

 hook in a component to manage different side effects.

 hook is used to create a direct reference to a DOM node (element). It takes an argument as the initial value and returns an object that has only one property - 

 This property holds the reference of the DOM node.

We can use this reference object to get the value of the element, set value of the element etc. This ref object also persists across re-renders. E.g -

      <button onClick={logValue}>Log Value</button>

 as the initial value to the ref object. It is then again passed to the ref attribute of the 

 tag which assigns the input tag as the DOM reference to the ref object. The input tag is now accessible via the ref object.

 button it logs the value of the input field on the console.

This hook provides a way to share data among functional components without having to pass data as props at every level.

To use this hook we have to first create a using 

. We pass an optional parameter as the initial value e.g -

const MyContext = React.createContext(10);

To use the context in a component we wrap that component with the 

<MyContext.Provider value={/* some value */}>

 hook in the child component to retrieve the context value.

import React, { useContext } from 'react';

The useMemo Hook is used to memoize expensive computations. This hook avoids the recomputation of the function across component re-renders by caching the result of the function with respect to the dependencies (generally the function's arguments) provided.

 It takes 2 arguments i.e. a function that needs to be memoized and an array of dependencies. 

const result = useMemo(function, [dependencies]);

The function is executed again only when there is a change in the dependencies. It helps in increasing the performance of the application by avoiding unnecessary computations. E.g -

import React, { useState, useMemo } from 'react';

  const [number, setNumber] = useState(0);

      return n * calculateFactorial(n - 1);

      <p>{`Factorial of ${number} is ${factorial}`}</p>

 function is memoized with the number variable as the dependency. Now, only when there is a change in the 

Custom hooks are self-defined functions that extract reusable logic that can be used across multiple components. All the rules that apply to react hooks also apply to custom hooks.

We can encapsulate multiple official react hooks and perform complex complex tasks inside custom hooks. E.g - 

import { useState, useEffect } from 'react';

  const [data, setData] = useState(null);

  const [loading, setLoading] = useState(true);

  const [error, setError] = useState(null);

        const jsonData = await fetch(url).json();

  const { data, loading, error } = useFetch('https://jsonplaceholder.typicode.com/users');

    return <p>Error: {error.message}</p>;

In the above example, we have created a custom hook 

 We are using this hook to fetch data from an API as well as display loading and error states. Notice how we have encapsulated multiple 

React hooks do help us make our code concise and cleaner but there are some practices we must follow to make out code maintainable.

Always use the hooks on the top level in functional components. Do not use them inside, loops, conditionals etc.

Always use hooks inside function components. Do not use them inside functions that don't return JSX.

 hook to share data among components that are nested across many levels. Avoid props drilling on more than 3-4 levels.

 hook to share global data that is needed across the entire application. E.g. - the current theme of the app, the role of the authenticated user, etc.

When using custom hooks keep the implementation more generalized which is used in multiple components. Do not use custom hooks for specific use cases.

Use the useMemo hook to cache the results of complex calculations.

Overall, React hooks are a relatively new feature in React but it has changed the way we write React code today completely. Hooks allow us to write more clean code which is also concise and more readable. By using different kinds of hooks you can create fully capable and performant react applications without having to deal with concepts of class components.

I highly encourage you to use hooks in your own applications to become a master React developer.

React hooks are a new feature in React but it has changed the way we write React code today completely. Learn about React hooks & their benefits with examples.

Master React hooks: Introduction with examples and best practices

Web development is divided into 2 categories i.e. "Frontend Development" & "Backend Development". The front end deals with the presentation of the web app to the user. It primarily deals with technologies like HTML, CSS and javascript and deals with building user interfaces.

The backend on the other hand is the side of the application which is not visible to the end user. The backend runs on the servers and its primary purpose is to handle the data coming from the frontend or to be sent to the frontend.

It involves operations like storing the data in the database, sending data to the front end, sanitizing form data, registering users, etc.

We must also understand that various backend frameworks have their strengths in building different types of architecture over other frameworks. E.g. if you need to handle a lot of requests concurrently use Node.js, use Python for fast development etc.

It is therefore necessary to understand the strength of all these frameworks and choose the right one for your project.

Do we always need a backend for our web application?

. Not all web apps need a backend. If we are making a website that doesn't have any dynamic data, doesn't need to accept any data from the user or stores anything on the server, we will be good to go with a 'static website'.

Static websites store pre-generated HTML pages on the server. Whenever a user visits a link, the corresponding static HTML page is sent as it is to the user by the server. It doesn't involve any processing by the backend.

However, most web apps nowadays are not static. Modern web apps do have some amount of dynamic content on them. E.g. YouTube, FaceBook and Twitter are all dynamic web applications. And most probably you will need a backend for your web app too.

Why do we need a backend development framework?

Modern programming languages like Python, Go and Javascript has all the capabilities to build up a server, write handler functions and generate templates etc... 

Then why do we need to use a backend development framework??

The primary use of a framework is to automate the nitty-gritty tasks necessary for software development. A backend framework helps us by abstracting the logic behind doing basic tasks such as running up a server, sending network requests, and parsing the incoming data so that we don't have to worry about all this stuff.

Therefore a backend development framework helps us by

Reducing the chances of bugs due to manual coding.

Top 10 best frameworks for your web application.

Listed below are the top 10 best backend development frameworks and the type of applications best suited to build with the corresponding frameworks.

Spring boot, released in 2014 is one of the most popular backend frameworks among backend devs. This Java based framework excels in building fast and scalable web applications. It powers the backend needs of companies like Amazon, Google, Microsoft, Accenture, Udemy, Intuit, PayTm etc.

 Spring boot is an extension of the spring framework. Spring boot reduces the boilerplate code required to initiate the application when using the Spring framework and makes development faster.

Use Spring Boot (or any Java based framework) if the speed of execution is the primary concern for the application. Also, note that java based apps consume a lot of memory (bec of JVM) so configure your server's RAM accordingly.

Embedded support for Jetty, Undertow and Tomcat servers. (default Tomcat)

Opinionated starter dependencies reduce boilerplate code.

 - spring boot introduces a lot of unused dependencies that increase the size of deployment files.

 - Spring boot is not suitable for large scale monolithic applications. However, it is still a good choice to build microservices which together can build a large application.

 - Spring boot can be overwhelming for novice developers. If you are not familiar with the spring ecosystem it can get challenging.

 - All Java based applications run on the JVM (Java Virtual Machine) and hence consume a lot of RAM.

ASP .NET Core is a free open-source framework created by Microsoft that is used extensively in backend web development. It is based on the C# language. The primary feature of ASP .NET is that it is faster and uses less memory than Java due to its natively compiled code.

 - ASP .NET core is a cross platform backend development platform. It means that applications built with it can run on Windows, Mac as well as Linux operating systems. It uses the same C# code across all platforms.

 - One of the major advantages of this framework is its performance. The code due to native compilation provides native speeds and also its memory footprint is very less as compared to Java.

 - ASP .NET Core comes with a lot of security features that are readily available for developers to use. It offers mechanisms for authentication, authorization, data protection and attack prevention. It also offers integrations with other major authentication providers.

 - ASP .NET Core requires less coding to build up an application. It helps developers to move fast and develop projects quicker than other frameworks.

Express is an open-source, node.js framework for building backend servers. It deserves special mention as this framework uses JavaScript for backend development. JavaScript is already regarded as the king of frontend development, with node.js it became possible to execute js code on the server as well.  However, creating backends with vanilla Nodejs can get a lot tricky and that's where express comes into the picture.

Express is a fast, extremely scalable, and very rapid development framework. It helps developers rapidly convert an idea into a product. It involves many middlewares that can make a developer's life easier and helps to move faster.

Express is regarded as the standard backend library for Nodejs. It is also a part of some popular full-stack development stacks such as the MEAN stack and MERN stack. These stacks follow the idea of js-everwhere and use javascript to build entire applications from scratch. It is also helpful as the frontend developers are also able to work on the backend without having to spend time learning other backend tech stacks.

 - JavaScript is already popular in the frontend development world and has a lot of user base. These developers can easily switch to working on the backend without much effort.

 - Node.js though single threaded, offers real-time performance due to its asynchronous non-blocking I/O architecture. It also uses the V8 javascript engine to convert js code into machine code which is the fastest javascript engine.

 - due to express being js based, we do not have to maintain a big team for the app development fewer devs can work on both frontend and backend as well. It is very helpful for startups and also improves communication.

 - Nodejs is very modular in nature. It doesn't come with any dependencies apart from the official node packages. It helps to ensure that we only use the code we need and the production bundle is very small in size. This feature of node js makes it one of the best choices for microservice and serverless architectures. We can spin up many lightweight Nodejs microservices and build a large application.

 - Express.js can be called a DIY framework due to its middleware architecture and minimalistic dependencies. It doesn't offer any ready-to-use robust security features. It rather leaves it upon the developer to implement the security features as they need them. It can also be considered an advantage for the devs who love control.

 - Although Nodejs offers features such as asynchronous non-blocking I/O for real-time speeds, it is still not considered a good choice for processor-intensive tasks. These tasks increase the wait time for other processes as all the tasks are handled by only one thread.

When to use Node.js for backend development?

You should use node js when you need real-time performance and the application relies more on database I/O operations and doesn't require processor-intensive tasks.

Django is a free and open-source leading python based framework. Django follows the MVC pattern and therefore it is a full-stack framework, however, it can also be used to build backend applications.

Django is a simple but feature rich framework that specializes in reducing the time taken in initiating the project to its completion. It offers many features such as an automated admin panel that is important for the content management of the application.

The most popular web apps built with Django are - Disqus, Spotify, Instagram, The Washington Post etc.

 - Django offers many features that make a dev's life easier when building a web application, such as an automated admin panel, sitemap generation, user authentication and credential management etc.

 - Django offers security against common threats right out of the box, such as XSS attacks, clickjacking, CSRF attacks, SQL injection etc.

 - Django shines in the category of easy-to-use development frameworks. It is very beginner friendly and has a low learning curve.

 - Django doesn't offer much versatility in building varied architectures. Django projects are monolithic by default.

- Django can lead to slow websites. The point to be noted is that it has less to do with the Python programming language, but more with unoptimized database queries, too many crud operations and the number of resources used.

Laravel is a free and open-source framework used to make Symfony based web applications that follow MVC architecture. Laravel is based on the PHP programming language.

Laravel is very popular among many developers with many experts regarding it as the best choice for backend web development.

Some of the popular brands using Laravel are:- 9GAG, Pfizer and TourRadar.

- Authentication is simple with Laravel. It abstracts important logic like hashing of passwords etc. and offers easy access to resources.

- Laravel offers inbuilt support for cache backends like Redis, Memcached, DynamoDB etc. Laravel also lets users write custom cache configurations. By default, Laravel uses the 'file' cache driver that stores the cache in the file system. For larger projects, we can use in-memory caches like Redis and Memcached.

- Laravel has powerful logging features that help to automate server logs. It uses a Monolog library that provides support for a variety of log handlers.

 - Development is slower when using Laravel as compared to other backend frameworks.

Ruby on Rails (aka Rails) is a popular free and open-source backend development framework based on the Ruby language. Rails like Laravel is an MVC architecture-based framework. Rails is extremely popular because of its simplicity and performance.

 - Ruby on Rails provides a huge collection of packages called gems that can be used by developers to add features to the applications without having to code everything from scratch.

 - Ruby on Rails creates automated tests for the models and controllers we write while building our applications. These skeleton test codes save a ton of time for the developers. We can even simulate browser requests for testing apps without a browser.

- Rails is a highly scalable framework. It is an apt framework for building apps that have to handle a high volume of users.

CakePHP is also a PHP based open source web development framework. It is greatly inspired by Ruby on Rails. It follows the MVC architecture.

 - CakePHP features a built in ORM that makes it easy to communicate with relational databases. The tables are represented as classes on which we can perform programmatic operations, call methods etc. and the changes are reflected on the database.

 - CakePHP is a highly scalable and very performant framework in terms of handling requests.

- The documentation of CakePHP is not very comprehensive as compared to other frameworks.

Gin is an open-source backend development framework written in golang. Gin is a relatively newer member of this list of best frameworks. What makes gin special is the speed and simplicity it inherits from golang.

Gin tends to be more performant than java spring boot and ASP .Net in many benchmarks. Another speciality of golang based frameworks is their very low memory footprint.

 - Gin is a simple and easy-to-use framework. It is easier for new developers to learn and start working with go/gin than other frameworks.

- Golang is a very high performant language. Gin claims to be 40 times faster than other frameworks.

 - Gin is a relatively new framework that has a much smaller community than other major frameworks like Spring Boot or node.js.

Flask is a free open-source, micro backend framework. Micro means that Flask does not come with many features packed in. It actually supports extensions that can be used to add features to the application. Flask uses Python language for development.

Here is a list of the top 10 backend web development frameworks you can use to build your own web applications.

Top 10 best backend development frameworks to build modern web applications.

Proof-of-Work (PoW) is the oldest consensus algorithm developed by the pseudonymous identity "Satoshi Nakamoto" who is also regarded as the inventor of the Bitcoin blockchain. Proof-of-work is used by some popular blockchain networks such as bitcoin and ethereum.

It is an algorithm in which one node "the prover", proves to other nodes "The verifiers" that a certainly expected computation is done. The provers then verify the result and if it is accepted by the majority of verifiers, it is considered valid and accepted.

In blockchains, the Proof-of-Work consensus algorithm is used to decide the next block to be added to the blockchain during the 

. The most common application of the PoW algorithm is the bitcoin blockchain.

In the Bitcoin blockchain, the transactions are grouped in a block to be mined. The block also stores some other information apart from the transactional data such as timestamp, block hash, previous block hash, nonce, network id, Merkle root etc. We won't go into the details of these properties as they're out of the scope of this article.

The nonce value is the solution that every node competes to find first. The nonce value should be such that when it is hashed along with the other block data generates a block hash that contains a specific number of zeroes at the beginning of the hash. The number of zeroes is determined by the current network difficulty at the moment. The miners go through many rounds of trial and error phases until the correct nonce is found.

The solution (here the nonce value) is called the proof-of-work. The miner who finds the nonce first shares it with other peers who then verify if the nonce is valid.

If it is valid the peers then incorporate that nonce value on their local copy of the blockchain and then share it with other peer nodes. This process repeats in a cycle until all the nodes on the blockchain implement that nonce value and add the new block on their local copies. The founder node of the nonce value is rewarded in bitcoins. This is how a new block is added to the blockchain.

Advantages and disadvantages of Proof of Work consensus algorithm.

PoW is a highly decentralized algorithm. All the nodes also have an equal preference in this algorithm.

With high decentralization comes high security.

Slow transaction speeds and expensive fees.

Very high energy consumption. All the nodes who compete but couldn't find the solution essentially waste energy.

Mining requires expensive equipment. With the increase in network difficulty, the equipment also becomes less effective.

Proof of Work is a consensus algorithm that helps blockchain networks to assent to a certain state of the network and remains robust.

As we all know that blockchain is a distributed, decentralized and immutable shared ledger of transactions, with nodes spanning across the globe. All the nodes also contain an entire copy of the blockchain on which they perform their operations. These nodes may also suggest different solutions for the new block to be added.

We also know that blockchains also maintain a common state(a common chain of blocks) for all the nodes.

In this scenario, a question that arises is - With the network of millions of globally distributed nodes, each one performing its operations at different time intervals, how does the blockchain network ensure a common state for all these nodes?

This problem is handled by the Consensus Algorithm used by the blockchain.

A consensus algorithm is a fault-tolerant procedure used in blockchains, through which all the nodes achieve an agreement for the common present state of the blockchain network.

Consensus algorithms maintain integrity and security in the network. They also help to establish trust among peers in a trustless environment.

They also make sure that any new block being added to the chain during the 

 is the same block being adopted by all the nodes in the network and thus maintaining a single source of truth agreed upon by all the nodes.

Now that we know what consensus algorithms are and what is their role.. let us find out what will happen if no consensus algorithm is used in a blockchain.

What will happen if no consensus algorithm is used?

During the minting process, when the nodes make changes to the local copy of the blockchain maintained by them, there will be no communication among their peers.

Due to this different nodes will adopt a different version of the new block possibly with different transactional data.

This will lead to the formation of many versions of the same blockchain each being different from one others.

Due to the formation of these parallel chains, the same address can hold different values in different chains.

E.g., let us consider a wallet address that had 5 Bitcoin initially, then spends 3 bitcoins. Now it owns 2 bitcoins on the network that recorded this change, while it may still hold 5 bitcoins on the version of the chain that couldn't record this change. It will give rise to security issues and double-spending problems.

Therefore, no single source of truth will exist and the integrity of the blockchain will be broken.

A deep dive into 2 most popular consensus algorithms

There are many standard consensus algorithms used by different blockchains. Blockchain projects sometimes also come up with their own invented algorithm. These algorithms have different working mechanisms and principles but ultimately a common goal.

In PoW algorithm all the nodes compete against each other to find a solution for a complex mathematical problem, the node that solves the problem first eventually adds the block to the blockchain and earn the reward. 

It is the most energy-consuming algorithm because all the power consumed by the rest of the nodes to find the solution is actually wasted.

Proof-of-Stake (PoS) is a low energy consuming algorithm. It is much more efficient that proof-of-work algorithm. Here, a validator is randomly chosen on the basis of amount of virtual currencies hoarded by the node. Therefore, the nodes that owns more currency has higher probability of receiving the validator responsibility and thus the reward.

This algorithm leads toward the centralization of power and promotes the holding of resources rather than spending.

The Ethereum 2.0 has adopted the PoS algorithm, discarding the PoW algorithm which is used in the previous version of the Ethereum blockchain, to reduce the wastage of electricity and natural resources.

Also ReadWe also know that blockchains also maintain a common state(a common chain of blocks) for all the nodes.

Proof-of-Stake (PoS) is a low energy consuming algorithm. It is much more efficient than proof-of-work algorithm. Here, a validator is randomly chosen on the basis of the amount of virtual currencies hoarded by the node. Therefore, the nodes that own more currency have a higher probability of receiving the validator responsibility and thus the reward.

This algorithm leads toward the centralization of power and promotes the holding of resources rather than spending. Ethereum 2.0 has adopted the PoS algorithm, discarding the PoW algorithm which is used in the previous version of the Ethereum blockchain, to reduce the wastage of electricity and natural resources.

A consensus algorithm is a procedure through which the nodes of the blockchain come to a common agreement regarding the present state of the network.

The term Smart Contract has been a matter of research over the years. It was until the advent of blockchain technology that it started gaining some momentum.

Note: Although many blockchains such as Hyperledger, Nem and Polkadot support smart contracts, in this article, we'll be talking about Ethereum as it is currently the most popular blockchain among smart contract developers.

The term smart contract was first coined in 1994 by Hungarian cryptographer Nick Szabo. He defined it as -

A set of promises, specified in digital form, including protocols within which the parties perform on the other promises.

In the context of blockchains, a smart contract is simply a program that runs on the blockchain. It resides at a specific address on the blockchain network. You can think of it as a set of agreements between a buyer and a seller, written in the form of code. It helps to perform safe transactions in a trustless environment.

Smart Contracts are similar to an Externally owned user account (EOA). They have an address, balance and they can send or receive transactions like user accounts too. However, unlike EOA, smart contracts cannot be controlled by any user. As a creator of a smart contract, you don't get any privilege on the protocol level. Although you can code functions that only the owner of the contract can use e.g. moving all the contract's balance or a self destruct operation.

The terms and conditions written in the smart contracts are accessible by everyone. Its execution is the same for all the users using the contract.

Once the contract is deployed on the blockchain, its code cannot be edited. The only way to modify it is to redeploy a new instance.

What are smart contracts on the Ethereum blockchain? An Introduction.

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Proof of Work (PoW) consensus algorithm.

What are the consensus algorithms in blockchains?

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