Thomas  Granger

Thomas Granger

1566026936

What is a Virtual DOM and why does React use it?

Real DOM

First things first, DOM stands for “Document Object Model”. The DOM in simple words represents the UI of your application. Everytime there is a change in the state of your application UI, the DOM gets updated to represent that change. Now the catch is frequently manipulating the DOM affects performance, making it slow.

What makes DOM manipulation slow?

The DOM is represented as a tree data structure. Because of that, the changes and updates to the DOM are fast. But after the change, the updated element and it’s children have to be re-rendered to update the application UI. The re-rendering or re-painting of the UI is what makes it slow. Therefore, the more UI components you have, the more expensive the DOM updates could be, since they would need to be re-rendered for every DOM update.

Virtual DOM

That’s where the concept of virtual DOM comes in and performs significantly better than the real DOM. The virtual DOM is only a virtual representation of the DOM. Everytime the state of our application changes, the virtual DOM gets updated instead of the real DOM.

Well, you may ask ” Isn’t the virtual DOM doing the same thing as the real DOM, this sounds like double work? How can this be faster than just updating the real DOM?”

The answer is virtual DOM is much faster and efficient, here is why.

How is Virtual DOM faster?

When new elements are added to the UI, a virtual DOM, which is represented as a tree is created. Each element is a node on this tree. If the state of any of these elements changes, a new virtual DOM tree is created. This tree is then compared or “diffed” with the previous virtual DOM tree.

Once this is done, the virtual DOM calculates the best possible method to make these changes to the real DOM. This ensures that there are minimal operations on the real DOM. Hence, reducing the performance cost of updating the real DOM.

The image below shows the virtual DOM tree and the diffing process.

The red circles represent the nodes that have changed. These nodes represent the UI elements that have had their state changed. The difference between the previous version of the virtual DOM tree and the current virtual DOM tree is then calculated. The whole parent subtree then gets re-rendered to give the updated UI. This updated tree is then batch updated to the real DOM.

How does React use Virtual DOM

Now that you have a fair understanding of what a Virtual DOM is, and how it can help with performance of your app, lets look into how React leverages the virtual DOM.

In React every UI piece is a component, and each component has a state. React follows the observable pattern and listens for state changes. When the state of a component changes, React updates the virtual DOM tree. Once the virtual DOM has been updated, React then compares the current version of the virtual DOM with the previous version of the virtual DOM. This process is called “diffing”.

Once React knows which virtual DOM objects have changed, then React updates only those objects, in the real DOM. This makes the performance far better when compared to manipulating the real DOM directly. This makes React standout as a high performance JavaScript library.

In simple words, you tell React what state you want the UI to be in, and it makes sure that the DOM matches that state. The great benefit here is that as a developer, you would not need to know how the attribute manipulation, event handling or the manual DOM updates happen behind the scenes.

All of these details are abstracted away from React developers. All you need to do is update the states of your component as and when needed and React takes care of the rest. This ensures a superior developer experience when using React.

React render() function

render() is where the UI gets updated and rendered. render() is the required lifecycle method in React. You can learn more about React lifecycle methods in detail from my blog post.

render() function is the point of entry where the tree of React elements are created. When a state or prop within the component is updated, the render() will return a different tree of React elements. If you use setState() within the component, React immediately detects the state change and re-renders the component.

React then figures out how to efficiently update the UI to match the most recent tree changes.

This is when React updates its virtual DOM first and updates only the object that have changed in the real DOM.

Batch Update

React follows a batch update mechanism to update the real DOM. Hence, leading to increased performance. This means that updates to the real DOM are sent in batches, instead of sending updates for every single change in state.

The repainting of the UI is the most expensive part, and React efficiently ensures that the real DOM receives only batched updates to repaint the UI.

Recap

  • Frequent DOM manipulations are expensive and performance heavy.
  • Virtual DOM is a virtual representation of the real DOM.
  • When state changes occur, the virtual DOM is updated and the previous and current version of virtual DOM is compared. This is called “diffing”.
  • The virtual DOM then sends a batch update to the real DOM to update the UI.
  • React uses virtual DOM to enhance its performance.
  • It uses the observable to detect state and prop changes.
  • React uses an efficient diff algorithm to compare the versions of virtual DOM.
  • It then makes sure that batched updates are sent to the real DOM for repainting or re-rendering of the UI.

Thanks for reading

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Further reading

React - The Complete Guide (incl Hooks, React Router, Redux)

Modern React with Redux [2019 Update]

Best 50 React Interview Questions for Frontend Developers in 2019

JavaScript Basics Before You Learn React

Microfrontends — Connecting JavaScript frameworks together (React, Angular, Vue etc)

Reactjs vs. Angularjs — Which Is Best For Web Development

React + TypeScript : Why and How

How To Write Better Code in React

React Router: Add the Power of Navigation

Getting started with React Router

Using React Router for optimizing React apps

What is DOM in JavaScript?

Angular 8 DOM Queries: ViewChild and ViewChildren Example

#reactjs #web-development #javascript

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What is a Virtual DOM and why does React use it?
Autumn  Blick

Autumn Blick

1598839687

How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

  • Performance: It delivers optimal performance.
  • Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
  • UI design: React Native enables you to design simple and responsive UI for your mobile app.
  • 3rd party plugins: This framework supports 3rd party plugins.
  • Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

  • Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
  • Near-native user experience: React Native provides several native components, and these are platform agnostic.
  • The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

#android app #frontend #ios app #mobile app development #benefits of react native #is react native good for mobile app development #native vs #pros and cons of react native #react mobile development #react native development #react native experience #react native framework #react native ios vs android #react native pros and cons #react native vs android #react native vs native #react native vs native performance #react vs native #why react native #why use react native

What are hooks in React JS? - INFO AT ONE

In this article, you will learn what are hooks in React JS? and when to use react hooks? React JS is developed by Facebook in the year 2013. There are many students and the new developers who have confusion between react and hooks in react. Well, it is not different, react is a programming language and hooks is a function which is used in react programming language.
Read More:- https://infoatone.com/what-are-hooks-in-react-js/

#react #hooks in react #react hooks example #react js projects for beginners #what are hooks in react js? #when to use react hooks

Mathew Rini

1615544450

How to Select and Hire the Best React JS and React Native Developers?

Since March 2020 reached 556 million monthly downloads have increased, It shows that React JS has been steadily growing. React.js also provides a desirable amount of pliancy and efficiency for developing innovative solutions with interactive user interfaces. It’s no surprise that an increasing number of businesses are adopting this technology. How do you select and recruit React.js developers who will propel your project forward? How much does a React developer make? We’ll bring you here all the details you need.

What is React.js?

Facebook built and maintains React.js, an open-source JavaScript library for designing development tools. React.js is used to create single-page applications (SPAs) that can be used in conjunction with React Native to develop native cross-platform apps.

React vs React Native

  • React Native is a platform that uses a collection of mobile-specific components provided by the React kit, while React.js is a JavaScript-based library.
  • React.js and React Native have similar syntax and workflows, but their implementation is quite different.
  • React Native is designed to create native mobile apps that are distinct from those created in Objective-C or Java. React, on the other hand, can be used to develop web apps, hybrid and mobile & desktop applications.
  • React Native, in essence, takes the same conceptual UI cornerstones as standard iOS and Android apps and assembles them using React.js syntax to create a rich mobile experience.

What is the Average React Developer Salary?

In the United States, the average React developer salary is $94,205 a year, or $30-$48 per hour, This is one of the highest among JavaScript developers. The starting salary for junior React.js developers is $60,510 per year, rising to $112,480 for senior roles.

* React.js Developer Salary by Country

  • United States- $120,000
  • Canada - $110,000
  • United Kingdom - $71,820
  • The Netherlands $49,095
  • Spain - $35,423.00
  • France - $44,284
  • Ukraine - $28,990
  • India - $9,843
  • Sweden - $55,173
  • Singapore - $43,801

In context of software developer wage rates, the United States continues to lead. In high-tech cities like San Francisco and New York, average React developer salaries will hit $98K and $114per year, overall.

However, the need for React.js and React Native developer is outpacing local labour markets. As a result, many businesses have difficulty locating and recruiting them locally.

It’s no surprise that for US and European companies looking for professional and budget engineers, offshore regions like India are becoming especially interesting. This area has a large number of app development companies, a good rate with quality, and a good pool of React.js front-end developers.

As per Linkedin, the country’s IT industry employs over a million React specialists. Furthermore, for the same or less money than hiring a React.js programmer locally, you may recruit someone with much expertise and a broader technical stack.

How to Hire React.js Developers?

  • Conduct thorough candidate research, including portfolios and areas of expertise.
  • Before you sit down with your interviewing panel, do some homework.
  • Examine the final outcome and hire the ideal candidate.

Why is React.js Popular?

React is a very strong framework. React.js makes use of a powerful synchronization method known as Virtual DOM, which compares the current page architecture to the expected page architecture and updates the appropriate components as long as the user input.

React is scalable. it utilises a single language, For server-client side, and mobile platform.

React is steady.React.js is completely adaptable, which means it seldom, if ever, updates the user interface. This enables legacy projects to be updated to the most new edition of React.js without having to change the codebase or make a few small changes.

React is adaptable. It can be conveniently paired with various state administrators (e.g., Redux, Flux, Alt or Reflux) and can be used to implement a number of architectural patterns.

Is there a market for React.js programmers?
The need for React.js developers is rising at an unparalleled rate. React.js is currently used by over one million websites around the world. React is used by Fortune 400+ businesses and popular companies such as Facebook, Twitter, Glassdoor and Cloudflare.

Final thoughts:

As you’ve seen, locating and Hire React js Developer and Hire React Native developer is a difficult challenge. You will have less challenges selecting the correct fit for your projects if you identify growing offshore locations (e.g. India) and take into consideration the details above.

If you want to make this process easier, You can visit our website for more, or else to write a email, we’ll help you to finding top rated React.js and React Native developers easier and with strives to create this operation

#hire-react-js-developer #hire-react-native-developer #react #react-native #react-js #hire-react-js-programmer

What is DOM, Shadow DOM and Virtual DOM?

In this lesson, we learn about the Document Object Model. We learn what the DOM, Shadow DOM, and Virtual DOM are and how they work. We also look at some of the practical examples to understand them better.

#dom #shadow dom #virtual dom

Anda Lacacima

Anda Lacacima

1594560120

How to Build React Component using React, React DOM and Babel

Now Let’s start discussing today’s topic.Today we’ll discuss about basic things you must know about React Library.It’s a famous front-end library which use in IT industry for business applications.Also day by day it’s getting updated.So, It will be much important for you to keep in touch with this library if you are willing/doing a_ job in IT industry _as it’s already a trending front-end technology now a days.So we’ll discuss it in details now and create your first React Component.

What is React ?

Simply, React is a JavaScript library that use to create _User Interfaces which runs on browsers _which was created by** Facebook._(one of the most popular ones, with over 100,000 stars on GitHub). It is the _view_ layer of an _MVC application**_ (Model View Controller)_

NOTE: React is not a framework.It’s a JavaScript library.

For a business application(client application) to be extremely successful it must be maintainable,manageable and_ re-usable.__Because when the business is expanding and when the customers asking for more improvement/changes the development team must be much responsible for making quick changes in the client application as soon as possible.That’s a more than 100% truth in _IT industry.So you must be a fast learner and a fast adapter when client requests rapid and complex changes in your business application.

Does React helps to overcome implementation complexity of client’s business applications

Yes.This is the most valuable and important thing which helps you when implementing a complex business application.React uses a concept called_ re-usable component__ which you may feel much comfortable with.It makes you re-use the same code in several places.Only thing you need to do is make changes to your props and __states.Using tiny components you could build your complex application in a simple way. __Also as this is a view part of the application it doesn’t depend(isolated with) on the _server state.

Components_ are like custom, reusable HTML elements, to quickly and efficiently build__ user interfaces_

_Now it’s time to try this with your own.I’m used _this online editor.It shows HTML, CSS, JavaScript sections clearly and separately.I recommend you to use it to make your first _React Component.

_We’ll create a simple HTML element which displays name and age of a __Person _using CSS styling as below(Image shows how a Person Component used to display information of two persons called Sanath and Pramod);

Image for post

person.figure

You only need both HTML,CSS files below to implement Person component using HTML and CSS.Use below code in editor to try this.

#components #react-dom #programming #react #babel