Understanding React — Component life-cycle – Bartosz Szczeciński – Medium

Understanding React — Component life-cycle

☞ 

#Reactjs #programming

  • In all other instances remember to use this.setState – DO – set initial stateif not using class properties syntax — prepare all class fields and bind functions that will be passed as callbacksDON’T – cause any side effects (AJAX calls is a somehow special case — componentWillMount does not differ much from constructor -…
  • DO – update state via this.setStateperform last minute optimizationcause side-effects (AJAX calls etc.) in case of server-side-rendering onlyDON’T – cause any side effects (AJAX calls etc.) on client function will be called in each update life-cycle caused by changes to props (parent component re-rendering) and will be passed an object…
  • DO – use for increasing performance of poor performing ComponentsDON’T – cause any side effects (AJAX calls etc.)call nextState)If the shouldComponentUpdate function is not implemented, or it decided that the component should update in this render cycle, another life-cycle function will be called.
  • == this.props.myProp) { – // this.props.myProp has a different value – // we can perform any operations that would – // need the new value and/or cause side-effects – // like AJAX calls with the new value – this.props.myProp – } – }DO – cause side effects (AJAX calls etc.)DON’T…
  • DO – cause side effects (AJAX calls etc.)DON’T – call this.setState as it will result in a re-renderAn exception to the above rule is updating the state based on some DOM property which can be only computed once a component has re-rendered (e.g. position / dimensions of some DOM nodes)….

React provides developers with many methods or “hooks” that are called during the life-cycle of an component, which allows us to update the UI and application state. Knowing when to use which of them…
Continue reading “Understanding React — Component life-cycle – Bartosz Szczeciński – Medium”

Understanding React — Component life-cycle – Bartosz Szczeciński – Medium

Understanding React — Component life-cycle

☞ 

#reactjs #JavaScript

  • In all other instances remember to use this.setState – DO – set initial stateif not using class properties syntax — prepare all class fields and bind functions that will be passed as callbacksDON’T – cause any side effects (AJAX calls etc.)componentWillMountThis is a somehow special case — componentWillMount does not differ much from constructor…
  • DO – update state via this.setStateperform last minute optimizationcause side-effects (AJAX calls etc.) in case of server-side-rendering onlyDON’T – cause any side effects (AJAX calls etc.) on client function will be called in each update life-cycle caused by changes to props (parent component re-rendering) and will be passed an object…
  • DO – use for increasing performance of poor performing ComponentsDON’T – cause any side effects (AJAX calls etc.)call nextState)If the shouldComponentUpdate function is not implemented, or it decided that the component should update in this render cycle, another life-cycle function will be called.
  • == this.props.myProp) { – // this.props.myProp has a different value – // we can perform any operations that would – // need the new value and/or cause side-effects – // like AJAX calls with the new value – this.props.myProp – } – }DO – cause side effects (AJAX calls etc.)DON’T…
  • DO – cause side effects (AJAX calls etc.)DON’T – call this.setState as it will result in a re-renderAn exception to the above rule is updating the state based on some DOM property which can be only computed once a component has re-rendered (e.g. position / dimensions of some DOM nodes)….

React provides developers with many methods or “hooks” that are called during the life-cycle of an component, which allows us to update the UI and application state. Knowing when to use which of them…
Continue reading “Understanding React — Component life-cycle – Bartosz Szczeciński – Medium”

Introducing the React Context API

  • The new React Context API is touted (at least on Twitter and a number of articles) as solving the need to use a state management tool, when I think in reality what it solves is easy dependency injection: Take something that lives at the top of your app and directly…
  • It essentially gives you an easy way to have state live at the top level in your component tree ( in this case) but “inject” it as a prop in a lower level component in the state tree.
  • A Consumer works hand-in-hand with the Context’s Provider, essentially allowing you to reach into your Context, and easily inject the Context’s value into a component, skipping many levels in the component tree.
  • Now that we’ve set up our Context and have created the Provider which wraps our app at the top level, we can now inject its into any of our lower level components.
  • When thinking of how to organize an app which uses React Context, I wanted to avoid having the Consumer code in the same file as the component which it “wraps”… the reason for this is because it makes it difficult to test the component in isolation.

We’ll take a look at the new React Context API, how to use it, what it does, and if it should replace Redux or MobX for your go-to state management option.
Continue reading “Introducing the React Context API”

Building Mobile Applications with React Native. A brief introduction.

Building Mobile Applications with #reactnative. A brief introduction.

  • If you open your App.js you’ll encounter something along the lines of: – Components are the core of React Native, every visual element of your app is a component.
  • This styling cheat sheet is very handy when you’re getting started to check on what properties are available when styling components, but for a complete description the go to place is the online React Native documentation.
  • There are many basic elements that React Native provides as starting points and building blocks for our components: Views, ScrollViews, Text, TextInput, Touchable components that respond to touch input, Image, etc… As your UI starts growing and you have the need to add more and more Native components you’ll start…
  • Props and State – These are important concepts that will bring functionality, customisation and the ability to reuse components throughout your application.
  • We’ve created a new component that makes use of props and state to render a few text elements to the screen of our app’s.

The number of mobile devices is estimated to cross the 5 billion [1] mark between 2018 and 2019. This is pushing the mobile application development market forward, with the ever increasing demand for…
Continue reading “Building Mobile Applications with React Native. A brief introduction.”

React links time! ⚛️ Super easy magic-move transitions ⚛️ Virtual DOM explained…

  • Wrap any element (not just images) in a component.
  • Add the same to create a transition between the elements.
  • A transition is made when an component is unmounted and another is mounted not later than 100ms.
  • The transition is made by cloning the unmounted and mounted components, adding them with position and CSS transformed from the source to the target position.

GitHub is where people build software. More than 27 million people use GitHub to discover, fork, and contribute to over 80 million projects.
Continue reading “React links time!

⚛️ Super easy magic-move transitions

⚛️ Virtual DOM explained…”

How to Use New React Context Api detailed � – codeburst

  • How to Use New React Context Api Context Api is available in the react16.3 so let’s build a counter using Context api.
  • Context Api helps us to pass down the data to the components without use of props at every component.In our counter app we only pass down one level.So Let’s install a react app using create-react-app – npm install -g newContext – cd newContext – npm start //to start dev serverNow…
  • app.js(using props)Now we are replacing it with context API Instead of using props in the Counter component.
  • First, we need to import NumberContext from our context.js file – app.js(uses context api)In line 39 above code tells first we are providing value to our component by wrapping our Counter component with the NumberContext.Provider.
  • The completed app looks like below image – That’s all in react documentation says Context is designed to share data that can be considered “globalâ€� for a tree of React components.

Now we are replacing it with context API Instead of using props in the Counter component.
First, we need to import NumberContext from our context.js file In line 39 above code tells first we are…
Continue reading “How to Use New React Context Api detailed � – codeburst”

An IDE for React.js – Arnaud – Medium

An IDE for React.js

☞ 

#Reactjs #javascript

  • Well, Reacto is a suggestion to the react community.
  • You can also get suggestions from npm registry right from Reacto.
  • Start creating new class-based react components now, and see how it looks anytime you’ll edit the file.
  • Today, I really hope that I can give something back to all of you, so that new developers start programming with the right tools, for free.
  • If you have any suggestions or feedback, feel free to comment below or open a new issue on github using “feedback” and “idea” labels.

It all started with a need for a software, free, that would provide everything for react development. I started working on this personal project two months ago and it is with an extreme joy that I am…
Continue reading “An IDE for React.js – Arnaud – Medium”

Exploring the React Context API with Provider and Consumer

  • It explains how to use React’s new context API for passing props down the component tree.
  • Basically, React’s context API takes the clutter away of passing mandatory props, that are needed by every component, down your whole component tree.
  • Therefore you could use React’s context API to give every component access to the colored theme.
  • As you can imagine, following this way every component that needs to be styled according to the colored theme could get the necessary information from React’s context API by using the Consumer component now.
  • This Provider component uses React’s context API to pass down the state implicitly.

React’s Context API is a powerful feature for passing props down the component tree without the need to tell components in between about them. React’s context creates a Provider and Consumer component that enable us to use this powerful feature …
Continue reading “Exploring the React Context API with Provider and Consumer”

How to Use New React Context API Detailed

  • React Context API is available in the react16.3 so let’s build a counter using – – Context API.
  • Context API helps us to pass down the data to the components without the use of props at every component.
  • Now we are replacing it with context API Instead of using props in the Counter component.
  • First, we need to import NumberContext from our context.js file – – In line 39 above code tells first we are providing value to our component by wrapping our Counter component with the NumberContext.Provider.
  • That’s all in react documentation says Context is designed to share data that can be considered “global” for a tree of React components.

how react context API works consumer and provider
Continue reading “How to Use New React Context API Detailed”

React’s safe Context API – codeburst

  • It’s purpose is to aid with that specific scenario ğŸ�‰ – But in older versions of React, you should not use it âš ï¸� – If you want your application to be stable, don’t use context.
  • You can read about the drawbacks of the current Context API here 📖 – The good news is there’s a new Context API in React@16.3! And it’s much better 🙌 – So, if you hadn’t heard of or used the Context API until now, there’s no need for FOMO 😅…
  • Here’s a demo of a theme toggle using the new safe version that’s currently obtainable in React@16.3ğŸ‘� – When would I need the Context API?It’s hard to think of an array of scenarios in which you’d need to use the Context API.
  • In many cases it will probably suffice ğŸ‘� – How might we handle it with the Context API?I’m not going to touch on the current release version of the Context API as the docs deter us from using it âš ï¸� – Instead we can take a look at how a solution…
  • Updating it might look like this – The consumer will pass a single render prop which is the current value for the Context ğŸ‘� – Much like Providers, you can have many Consumers within the component tree.

Ever needed to pass a prop down through many levels of the component tree? Did you do it manually? It’s not ideal is it? Did it have to pass through components where it looked out of place? The…
Continue reading “React’s safe Context API – codeburst”