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.
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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…
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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
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What the React Native docs forgot to tell you about animations

  • The last animation function is Animated.decay() and has some specific use cases.
  • Based on that and a deceleration value, it calculates what the end value is and how long the animation should take.
  • this.animatedValue = new = new Animated.ValueXY({x: 15, y: 0, y: 0});getTranslateTransformThis method with transform your {x: 10, y: 200} value to a directly usable transform.
  • this.animatedValue = new Animated.ValueXY({x: 10, y: 200});Animated.Value style={{ – transform: /// is short for Animated.View style={{ – transform: [ – {translateX: this.animatedValue.x}, – {translateY: this.animatedValue.y} – ] – }} /stopAnimationStops any running animation.
  • It has a callback with the final value after the animation has = { – console.log(‘finalValue: ‘+ finalValue) – })resetAnimationStops any running animation and sets the value back to its original value.

React Native is great. It’s pretty awesome to be able to build a native app with only JavaScript knowledge. One of the things I like most is making the animations, it can add so much to the…
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85 -⚡️Learn To Code with Rik Lomas – Thunder Nerds

⚡Learn To Code with Rik Lomas -->  @riklomas @superhi_ #js #reactjs

  • In this episode we get to chat with Rik Lomas: CEO of SuperHi and author of Learn To Code Now.
  • We get to know Rik as a crazy cat-loving englishman from Manchester currently residing in NY.
  • We discuss how Rik got his start and what fanned the flame of his love for teaching.
  • We also talk about how and why Rik started SuperHi, and its value to the community.

In this episode we get to chat with Rik Lomas: CEO of SuperHi and author of Learn To Code Now. We get to know Rik as a crazy cat-loving englishman from Manchester currently residing in NY. We discuss how Rik got his start and what fanned the flame of his love for teaching. We also talk about how and
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Slide Up and Down with React Transition Group

Slide Up and Down with #reactjs Transition Group

  • I already solved the vertical slide dilemma with jQuery, but I needed to implement it for React Transition Group.
  • When items are entering a list, we want them to fade in and smoothly slide the surrounding elements away, instead of brutally shifting our interface.
  • Transitions work by easing from one initial value to an other defined one.
  • The problem with vertical sliding is that most HTML element containers do not have a predefined height, but rather adapt this value to fit the content.
  • My approach is to use the CSSTransition component callbacks to animate a negative margin and slide our items from the top.

Some UI effects are very simple, yet difficult to achieve. I already solved the vertical slide dilemma with jQuery, but I needed to implement it for React Transition Group.
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Simple, Touch-Friendly carousel component for @reactjs #reactjs #react-component

Simple, Touch-Friendly carousel component for @reactjs #reactjs #react-component

  • The basic carousel sample.The Carousel component returns a callback function with the following arguments.
  • and must be passed down to the elements – – But the Carousel component also returns other arguments, like , , , , , – – For the component to work, for example, on mobile devices, set the value to true for touching.
  • Set the value for and place the argument in your jsx template – – When you stop moving your mouse triggers a function which calculates the position of the elements.
  • For example, you want to fetch data or trigger some function when you reach the end of the carousel.
  • The default value for is 0 – – must be passed to the component – – Use the arguments and from the callback.

react-awesome-carousel – Simple, Touch-Friendly carousel component for React.js
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Using RxJS with React.js: Part 3 — Dispatching events from Component

  • (Check out FrintJS on GitHub for more documentation on combining the power of RxJS with React)Illustration of unidirectional flow between Subject and ComponentUnidirectional cycleEarlier we saw an example of HoC streaming props to the base component.
  • Let’s now look at ways how we can dispatch events from inside the base component, update some value, and the updated value will then be streamed back to the component completing one unidirectional cycle.We can take the example of a form input field.
  • To keep things simple, let’s say BehaviorSubject is a kind of Subject, that can already start with an initial value.import { BehaviorSubject } from ‘rxjs’;const subject$ = new = console.log(x)); // prints `foo` right awayThe base Component with form inputLet’s say this is our base component:import React from ‘react’const MyComponent =…
  • First one is a stream of the input value, and the latter for handling the change.import { BehaviorSubject, Observable } from ‘rxjs’;const formInput$ = new BehaviorSubject(‘foo’); // with initial valueconst handlers$ = Observable.of({ handleChange: value = formInput$.
  • scan(function (props, emitted) { return { …props, …emitted }; });Observing the base ComponentNow that we have the props$ observable ready, we can integrate it with our base complement easily using the observe function from FrintJS:import { observe } from ‘frint-react’;const ObservedRoot = observe(function () { return props$;})(MyComponent);Now you can stream…

Earlier we saw an example of HoC streaming props to the base component. Let’s now look at ways how we can dispatch events from inside the base component, update some value, and the updated value will…
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4. Four ways to style react components – codeburst

  • All depend on your personal preferences and the specific complexity of your application.If you want to add just a few style properties, then inline styling is the best option.When you want to reuse your style properties in the same file then style-component are perfect.When your application is more complex I…
  • Instead they are specified with an object whose key is the camelCased version of the style name, and whose value is the style’s value, usually a string.We can create a variable that stores style properties and then pass it to the element like style={nameOfvariable}We can also pass the styling directly…
  • CSS ModulesA CSS Module is a CSS file in which all class names and animation names are scoped locally by default.
  • Great article about css modules here.Similar to css we import css file import styles ‘.
  • Styled-components 💅Styled-components is a library for React and React Native that allows you to use component-level styles in your application that are written with a mixture of JavaScript and CSSFirst we need to install styled-components librarynpm install styled-components –saveNow we can create a variable by selecting a particular html element…

There are four different options to style React components. All depend on your personal preferences and the specific complexity of your application. In React, inline styles are not specified as a…
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Number Flipping Effect With ReactJS

Number Flipping Effect With ReactJS

  • In this tutorial, we’re going to use the excellent React Animated Number library to program a currency display component that changes color based on value.
  • You can check out an example with our production all at Cryptodamus – – If you enjoyed this tutorial, make sure to subscribe to our Youtube Channel and follow us on Twitter @pentacodevids for latest updates!

In this tutorial, we’re going to use the excellent React Animated Number library to program a currency display component that changes color based on value. You
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