React Tutorial: A Comprehensive Guide to learning React.js in 2018

  • These components are defined either in pure JavaScript or they can be defined in what the React team calls “JSX”.
  • The reason the React team went with this approach is because, since the virtual DOM is a JavaScript representation of the actual DOM, React can keep track of the difference between the current virtual DOM(computed after some data changes), with the previous virtual DOM (computed befores some data changes).
  • In more layman’s terms, because manipulating the actual DOM is slow, React is able to minimize manipulations to the actual DOM by keeping track of a virtual DOM and only updating the real DOM when necessary and with only the necessary changes.
  • The process looks something like this, – – Some user event which changes the state of your app → Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.
  • Signal to notify our app some data has changed→ Re-render virtual DOM -> Diff previous virtual DOM with new virtual DOM -> Only update real DOM with necessary changes.

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Infinite scroll techniques in React – LogRocket

Infinite scroll techniques in #reactjs – LogRocket  #javascript

  • Infinite scrolling technically requires adding a scroll event listener to the window object or a certain div.
  • Implementing from the ground upAs mentioned earlier, infinite scroll is about attaching event listeners to DOM elements while watching for when the scrollbar hits the bottom of the div.
  • Look at the render function of this Component below: – Say you want to load more li items into the ul tag each time the div with the class App gets to the end of the div, how do you tackle this problem?
  • Here is what the final component should look like: – Using an infinite scroll libraryWhile the first method showed how relatively easy it is to implement infinite scroll in React applications, you might not be so content to implement event listeners yourself.
  • Instead, there is hasMoreItems which is used to tell the Infinite scroll component to detach the event listenerAn alteration to the loadMore function, which sets the hasMoreItems state to false once the items his 200ConclusionAnd there you have it, two different methods that allow you to implement infinite scroll in…

In this tutorial, Ogundipe explains two methods of implementing infinite scroll in React
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Optional Chaining Operator in JavaScript – Bene Studio

  • var user = { name: ‘Joe’ } – var zip = user.address.zip // ⚡⚡⚡Uncaught TypeError: Cannot read property ‘zip’ of undefinedIn this example we expect user.address.zip to exist but for some reason the address is missing from the user object.
  • Workaround #1: Logic Expressionsvar user = { name: ‘Joe’ } – var zip = user – user.address – user.address.zipNoisy and verbose.
  • Workaround #2: Ternary Operatorsvar user = { name: ‘Joe’ } – var zip = – user === undefined – ?
  • Workaround #3: Try-Catchvar user = { name: ‘Joe’ } – var ziptry { – zip = user.address.zip – } catch (error) { – zip = null – }Breaks control and has own scopes.
  • bin/babel index.jsThe Transpiled CodeTranspiled version of the index.js above: – var _user$address;var user = { – name: ‘Joe’ – };var zip = – user == null – ?

All of us usually confronts the situation where an expected member of a property chain is undefined or null. In this example we expect user.address.zip to exist but for some reason the address is…
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Introducing Rekit Studio: a real IDE for React and Redux development

#reactjs , with #Redux to #code there is now this:

  • As an IDE, besides code editing, Rekit Studio provides the capability for code generation, dependency diagraming, refactoring, building, unit tests, and a meaningful way to navigate code.You will no longer care about how to setup the project, config webpack, or organize your folder structure.
  • That’s what makes Rekit Studio different from other code editors like Sublime Text and VS Code.See the quick demoBefore the introduction, you may want to see a quick demo video about how to use Rekit Studio to manage Redux actions.From the video, we can see that all we care about is…
  • Then the project explorer can show the project structure in a meaningful way, like this:Project ExplorerRekit Studio knows the features of those project elements, like which actions are asynchronous (with blue mark “A”), which components connect to the Redux store (with green mark “C”), and which components are managed by…
  • This caused our project to become hard to maintain in a short time.Now with Rekit Studio, you can right click a component or action to move, and rename or delete it just like you do with other IDEs like Eclipse for Java or Visual Studio for .Net.
  • If you want to create some new elements like selectors, or you want to alter the default code boilerplate (like using `redux-saga` instead of `redux-thunk` for async actions), you can create plugins to do it.See more about the plugin system here.Command line interfaceBesides Rekit Studio, there is another command line…

We’re very excited to announce the stable release of Rekit Studio, a complete IDE for React, Redux and React Router development! Though it’s maybe new to some of you, it has helped us build…
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Introducing Sideswipe: a cross-platform carousel for React Native

  • Ideally we want to animate based on scroll position, not index changes, which would provide a much smoother effect.Old solution for handling transitions between itemsI knew I could add an Animated.event to the FlatList and pass the animated value to the child components but the value would be the raw…
  • This means the components using the animated value would have do some math to figure out if they were the active index.
  • It also updates any time either one of the underlying animated values updates.What this means is we can divide the scroll position by the width of a child item (which is a required prop) and that will give us an animated value starting at 0 and ending at the length…
  • Now child components can animate based on their index instead of scroll position but the animation will still be based on scroll position under the hood.
  • Here’s what that looks like in code:Using Animated.divide to get animated value for carousel itemsNow each carousel item gets an animated value they can use to create entrance and exit animations based on their index in the list, not the scroll position of the underlying FlatList, this provides a much…

Recently I found myself in need of a flexible carousel solution that could support some pretty tough requirements, mainly: My first attempt was to utilize open-source and use something someone else…
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What is MobX? Explain like I am five 👋

  • By beginner, I expect at least to know what global variables, modular architecture and scope are.
  • Since this beginner doesn’t really know what is (thus also what state management is), I’d like to compare MobX to a fancy global variable(s).
  • Some really really novice developers might make it work with global variables and be happy.
  • Then, MobX will do so much more than just keep it accessible to other modules, it can execute some actions (calculations) to them, let your modules know as soon as some property changes, etc.
  • While MobX is just another state management tool, in my opinion it’s the best one to compare to ease of understanding global variables.

Answer (1 out of 2): Imagine mommy is making pancakes for you and your siblings. It’s a birthday party! She will keep bringing pancakes as long as you are hungry and having fun. She will also keep track of how many pancakes you ate and she knows what kind of pancakes you…
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Introducing React Paginating 🎉🎉🎉 – Dzung Nguyen – Medium

Introducing React Paginating 🎉🎉🎉 @davidnguyen1791 

#Reactjs #Javascript #Webdev #Tech

  • Introducing React Paginating 🎉🎉🎉Today, I am happy to announce a React Paginating component.gif react-paginating demoThere are some popular components which help us to solve pagination problem such as react-paginate, react-pager, … Now there is another one.
  • It’s called react-paginating with a different approach.How “react-paginating” is uses Function as Child Components pattern which allows a component to publish any variables, states or functions to the outside as input params of a function which is going to be used for handling logic and rendering the UI.Here are some…
  • The formula to calculate totalPages:const totalPages = Math.ceil(total / limit);pageCountHow many pages you want to display.I.e:pageCount = 5with pageCount = 5pageCount = 9with pageCount = 9currentPageThe page currently you are visiting.
  • The component calculates and publishes props which allow controlling UI.
  • After that, you might put your CustomAnchor / somewhere on your “storybook” or components manager.DemoConclusionIf you see it is useful for you.

There are some popular components which help us to solve pagination problem such as react-paginate, react-pager, … Now there is another one. It’s called react-paginating with a different approach…
Continue reading “Introducing React Paginating 🎉🎉🎉 – Dzung Nguyen – Medium”

Development Driven Testing (ReactJS) – Ahsan Naveed – Medium

  • Development Driven Testing (ReactJS)Apparently it is a thing — while constructing UI’s with React we need to have components before we test the expected UI behavior.
  • There is still some TDD involved as you develop components you want to make sure that the HOC’s you are developing/engineering works the way you want them to work.
  • The normal workflow of structuring these components will be, to have the site running on localhost:port and thinking the code as you go.
  • If you would like to implement feature x in your web application it would be a good idea to see if there exists a package that can x-ify your app for you.Finally, would like to share the article below: the article above, the most important advice is to construct the…
  • My personal advice extends the advice above i.e. implement static components and then write tests to validate their UI behavior and then do whatever the senior developer says.

Apparently it is a thing — while constructing UI’s with React we need to have components before we test the expected UI behavior. There is still some TDD involved as you develop components you want…
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Introducing Rekit Studio: a real IDE for React and Redux development

Introducing Rekit Studio: a real IDE for React and Redux development

#reactjs #javascript

  • As an IDE, besides code editing, Rekit Studio provides the capability of code generation, dependency diagram, refactoring, build, unit tests and a meaningful way of code navigation.
  • That’s what makes Rekit Studio different from other code editors like Sublime Text, VS Code.See the quick demoBefore the introduction you may want to see a quick demo video about how to use Rekit Studio to manage Redux actions.From the video we can see with Rekit Studio, all you care about…
  • I introduced the practices in two previous articles:Based on the pattern, Rekit Studio knows which files are components, which are actions, where routing rules are defines and so on.
  • Then the project explorer could show the project structure in a meaningful way like below.Project ExplorerRekit Studio knows feature of those project elements, like which actions are asynchronous (with blue mark ‘A’); which components connect to Redux store (with green mark ‘C’); which components are managed by React Router (with…
  • This will cause our project becomes hard to maintain in a short time.Now with Rekit Studio, you can right click a component or action to move, rename or delete it just like you do with other IDEs like Eclipse for Java, Visual Studio for .Net.

We’re very excited to announce the stable release of Rekit Studio, a complete IDE for React, Redux and React Router development! Though it’s maybe new to some of you, it has helped us build…
Continue reading “Introducing Rekit Studio: a real IDE for React and Redux development”